I'm in Sierra Madre, and I wandered into the executive suites before going to the kitchen. Now it won't let me back down the elevator, and the Emergency Door won't open (even though I unlocked it) because of the gas that needs to be shut off. How do I get out of the executive suites and down to the kitchen? My last save game before entering the executive suites was hours ago, and I really don't want to have to do all that over again. Thanks!

The gas you need to shut off is in the executive suites; it's unconnected to the other gas quest in the kitchens. Look for a valve in one of those utility rooms (I think it's the one with the workbench but I'm not sure).
Pretty sure you should be able to leave the suites after that.

What i did ( i got stuck several times) was to run around and search the whole place and die... and than repeat it until you find the gas valve. Or what you could do is to search for help on youtube or fallout wiki
I got stuck in the kitchen and searched the whole [censored] place until the gas valves didnt have anywhere to hide haha
Hacking computers and turning off security and picklock every door you see is also very usefull.