I'm going to go from a personal/"selfish" side: I'd choose either faction in the civil war. Other than a change in methods to get things done, it would have little difference to me which side wins. for the empire: I'd use my influence as archmage, harbinger of the companions, and Dovahkiin, to influence Imperial policy and militarization. for the stormcloaks: I'd lead Ulfric's faction to victory, then immediately challenge him for the title of "High King". I'd absolutely destroy him, call a moot, and, due to my official and unofficial powers and titles, would become the elected High King. I'd waltz into Whiterun, stab Vignar in the face, reinstate Balgruuf, travel to Markarth, order the reinstatement of Igmund as Jarl. I would kill any influential characters who oppose me, dispose of the useless Jarls like the Jarl of Riften, and bring Maven in, who, considering her ties and partnership to MY Thieves Guild, and her supposed but false claims to have sway in MY Dark Brotherhood, I'm more than certain I could keep her in line. I'd create a more standard military uniform and leave the old stormcloak atire to the guards of Eastmarch, and reinstate the uniforms of the guards of Whiterun, Markarth, Morthal, Falkreath, and Solitude. For military uniforms, I'm thinking perhaps steel plate and scale armor, with the nice old symbol for Dovahkiin on a tabard overlay. I'd order immediate improvements to the Grey Quarter in Windhelm, open the doors of Skyrim's cities to Khajits, and open military recruitment to all races, and, of course, demand an oath of allegience to ME. Not the Jarls. ME. I'd also immediately send out peace feelers to the Empire, and given my rather respectible set of achievements would probably achieve some form of ceasfire or armistice or even a non-aggression pact. An open alliance would be more long term, as time must pass for old wounds to heal, and rushing these things can do more harm than good. I would bring back Talos worship, and order the internment of all Thalmor operatives, officials, and soldiers in Skyrim. Perhaps I would keep them in an internment camp but treat them hospitably. Perhaps I'll organize death camps and process them. Who knows? I'm unpredictable like that. With the defeat of Alduin, I too would sit Esbern and Delphine down and explain things to them. I highly doubt the conversation would ever come to blows. Perhaps stubborn and bitter disagreement, but there's no chance they would try to harm me after everything I've done, and given the oaths they swore. I would expand Blades membership and extend invitations to all the companions I met in my travels. Like the new Kingdom of Skyrim military, they would swear an oath of loyalty to me and me alone. I'd use Solitude's key harbor to extend trade to Hammerfell and also construct my Skyrim Navy. I would welcome Altmer and Bosmer immigrants to Skyrim, but put them through a thorough screening process to ensure none are Thalmor agents. To fund all this after a civil war, I would be forced to institute a small Kingdom tax, payable by all citizens of Skyrim, in addition to a small levy on the Jarls personally. (this tax idea is optional depending on how desperately it is needed) Most importantly, i would establish a council, with representatives of each of the nine holds appointed by joint agreement of me and the respective Jarl (for example, Balgruuf and I have to agree on the candidate). Last but certainly not least, I would become a vampire, and thus immortal, to ensure no successor be corrupted, no replacement indifferent, no son or daughter enacting policies against my design. I would serve. No one would stand in my way. No one would reshape my vision of my kingdom. I would rule. Indefinitely.
You forget to take safety measures because you need to sleep during the day. and have all the weaknesses of a vampire...