As far as optimizing combat enchanting, alchemy and smithing are usually 3 perk tree someone would want to explore especially for smithing with a character wearing armor or using melee/ranged weapons.

Otherwise I feel alchemy and enchanting are key either way you go as far as optimizing gear and buffs for combat situations.

Personally I prefer a two handed weapon for my main build and rely heavily on close quarters combat.

I have seen builds where the character simply summons/reanimates npcs along with their companion and allows them to fight for them. This method would exlcude the idea of weapons or armor being needed, but alchemy and enchanting can still optimize this method.

For my main build I place my points in the following:

Two handed - 19
alchemy - 15
smithing - 10
block - 9
enchanting - 13
light armor - 10
archery -4

As I said this is a build that is based off melee combat. I have 4 points in archery in the event I am incapable of reaching my enemy with melee attacks.

as a complimenting dragon shout I would usually use elemental fury to increase weapon attack speed.

For smithing, I always go the heavy armor route. Daedric just looks awesome and I prefer the heavy armor perks to the light armor ones. I go to daedric and select arcane blacksmithing and that's it. For alchemy, you really only need to go up to benefactor, but you can go a bit higher if you want more convenience. Enchanting, I never use frost/lightning spells and I use magic resistance over elemental resistance, so I get every enchanting perk including fire but leave the last two blank.

It's up in the air from there, really. You can get more creative in any of the schools of magic, delve deeper into sneaking/pickpocketing, or get some extra speech perks, etc. Lock picking is one of the main skills I'd say you could put in, max, 2-3 perks and be just fine. The rest of it is pretty meaningless.

19 perks in 2-handed? Only 8, maybe 9 are useful. Hell, by the time you have 5/5 in Barbarian and have anything in enchanting you will be one or two hitting basically anything besides Dragons, Dragon Priests, and Death Overlords.

I wouldn't go up to 81 on any characters so far. Breaking 40 is almost enough.

All light armor, all 2handed, 5 in the main blocking perk - 1 in the slow time one, 6 points in smithing, 3 points in archery. Voila.

I guess I could expand on that with some alchemy or putting the passive magic resists in alteration.

http://skyrimcalculator.com/#89496
something like this

Until 50 its also completely viable just without smithing, 1handed, light armor and block - with archery and summons

On my current mage character?
Destruction, Enchanting, and Conjuration would be the ones I'd focus on first.

On my first character (warrior/rogue) I focused on 1H, Light Armor, Smithing, Pickpocket, and Sneak.

"Where would you spend your 81 perk points?"

Spread it out somewhat evenly.

I agree with Waen spread them out somewhat evenly.

i take any perk that gives a boost to my character's abilities.

since i want my character to do everything well i perk everything.

No points on Block or Armor; they can be fixed up with enchants. Same with one/two handed, unless you want the decap perk.

Although block does have some nice bonuses to it, like shield charging (although after a while that perk no longer works).

Oh! Sounds like shield charging was a well-spent perk, then!

The skill system is so terrible that I do not enjoy putting any point down. It is choosing the lesser evil over the bigger evil most of the time. There are so many perks that will make me regret my choice, because they get useless after a while. It feels as if Bethesda hates me.

it is only through trial and error that we learn what perks help.

i have found that most perks up to mid level still benefit higher level characters.

I can't find a bad thing about light armor and 2handed (although I find the weapon critical bonus to be optional). They're simple and nothing particularly superfluous about them.

I can barely spend 40 perks before I run out of things I want.

If I were to go up to 81, I'd just make a godly spellsword type. Just for kicks. Usual 1 handed/heavy armor warrior skills, with a little resto/alteration and a lot of destruction. I wouldn't use all of it, but I guess it'd be cool to have one character with multiple playstyles. Seems like the character Todd was playing in the pre-release videos was like this.

On both of my characters (one heavy armor and one light armor) I got all on the Heavy Smithing side up to Dragon (for weapons on the light armor wearer).

On the light armor character:
For fighting I wear Legendary Forsworn (female character) smithed past the cap.
I get Enchanting up to Extra Effect.
I took all the 'beneficial' Alchemy Perks.
I took all the Sneak perks.
I took all the 1-H perks that apply to daggers.
I took all the Light Armor perks except Wind Walker (I put Fortify Stamina and Health Regen enchants on body pieces).
I took 4 Illusion perks (including Quiet Casting) to help with Invisibility spell.
I don't enchant weapons because I can Smith them powerful enough and it gets tiresome recharging weapons all the time.
At LVL 67 I still have 4 perks free and I can't see anything that I "need".

It's been a while since I played the Heavy Armor character, but much of the above was the same.

I don't think I could spend 81 perks. Doubt I'd want to level that far, and at level 48 I have 5 left unspent (though that character intentionally uses few skills, and avoids certain perks that might be usable even if not all that useful).
Lessee, I think its
10 x Two Handed (5 Barbarian, Champion's Stance, 3x Deep Wounds, Devastating Blow)
3 x Speech (1x Haggling, Allure, Merchant)
5 x Alchemy (5x Alchemist)
7x Heavy Armor (4x Juggernaugh, Well Fitted, Fists of Steeel, Cushioned)
3x Stealth (2x Stealth, Muffled Movement)
8x Enchanting (5x Enchanter, Insightful, Corpus, Extra Effect)
7x Smithing (Steel, Arcane, Dwemer, Orcish, Ebony, Daedric, Dragon)

Some of those I could easily do without; For example, I've made ONE piece of dragon armor (a helmet), and only bought Fists of Steel and Cushioned because I didn't need the perks for anything else and was getting sick of dying from falls when trying to get good screen shots / take shortcuts.

I only have 1 character, he is a lvl redguard battlemage So for me enchanting was a must, (destruction spells cost too much so I bring them down to 85%) I also put points in onehand destruction, conjuration, illusion. I also points in backstab so I could get assainations with the bound swords which are my main weapon as a battlemage. After playing the guy since day one I feel like there is still much for him to do...

Well on my bretoness mage (currently about level 40 with 100 alteration illusion and enchanting)
all illusion (except master spell cost)
all alteration (still wondering if i should just wear armored gauntlets and armored boots, so not mage armor yet, still considering master spell cost but the time it takes to cast dragonhide is still quite unappealing)
all in destruction, except extra shock damage and master spells
middle path in enchanting
maybe 6 perks in restoration, 50% extra magicka recharge, novice apprentice and adept spell cost, and also the perk that makes healing spells heal more.
I want to do conjuration but i realized too late that the alteration perk atronarch also absorbs spells on self
and if i end up having spare perks i might do a little sneak

Quick Reflexes is an amazing perk. Also, if you don't have an ethical problem with it, Quick Reflexes is bugged in that taking the perk automatically raises your blocking ability to the cap (85%).

I thought it was the 'Deflect Arrows' perk that did that instead of 'Quick Reflexes'?

Something like http://skyrimcalculator.com/#90221

Pretty much covers all my needs, since I mainly use stealth, without the use of magic.

Oh, I can. The bonuses are all too high. All those 20%-25% should better be 5%-10% values. It is what makes them superfluous.

You have no need to put all 5 points into the base perk of light armor.

The secondary skill groups like Smithing, Enchanting and Alchemy only add to it, while the offensive and defensive skill trees were designed as standalone skills, but who really plays the game like this?

It is all a bit too nerdy even for an RPG.

Correct, I typed the wrong one.