I was going heavy NCR 'til I had to kill the Brotherhood, which at that point I when Wildcard.

First playthrough I'm going full NCR, got the Khans and BoS to join them. 

" @Zurv: Thats true, but only if  you didn't complete the optional Oust the Elder sidequest for the BOS. If you did that, then you can't convince them of shit.  "

At this point, I'm my own man. I was going full NCR then when it came to seeing I can destroy the Hoover Dam all together then I sided with Yes Man. I just love how he agrees with everything. 

Did NCR first, loaded back, then did Yes Man.

I was going to go full Caesar until I met him. As cool as it is that Bill Rawls (John Doman) voices him, that guy needs a bullet in his brain. Now I'm going full Wild Card because House seems kinda shady to me and Yes Man is awesome. I'm going to do different playthroughs for all of these so I can get the achievements, but it's Wild Card for my real playthrough.

Am I seriously the only one who sided with House on the first playthrough? 
 
That dude is like alternate history Walt Disney, but with a robot army.

Can you side with more than one faction into the end game? Is there a point where you're forced to definitively choose one? Are all the factions viable as end game options, even the minor ones (Powder Gangers, Kings, etc.)? Minimize spoilers please.

I'm going NCR right now, but they really set the game up to make the NCR the first you encounter anyways. I do plan on at least one more playthrough. Don't know who I'll support on that one.

I thoroughly enjoyed working with the Legion. The only disappointment for me was that I couldn't become Caesar myself. Oh well, I suppose iconographic homage will have to suffice.

Something this thread has taught me is it seems that I have been on the right path by trying to complete side quests before progressing the main quest as much as possible.

NCR but i think i may go Yes Man to avoid doing some shit quest (brotherhood of Steel im looking at you)

" Can you side with more than one faction into the end game? Is there a point where you're forced to definitively choose one? Are all the factions viable as end game options, even the minor ones (Powder Gangers, Kings, etc.)? Minimize spoilers please. "

There are 4 "main" factions NCR and Legion being 2 of them, the other 2 are less factions and more of individuals. You can only pick one main faction. A choice has to be first made as to wich of the 2 independents you will choose, but the proper choice is a bit later when you have to choose between NCR, Legion and the one you chose before. The "minor" factions you can mix and match as you please help them or annihilate them, some of them can be persuaded to help you out at the end or to not meddle at least. They mostly figure in the types of endings you are going to get with them. There is however 1 minor faction that is very important to the game and their support pretty much decides with which of the main factions you side with (unless you wipe out that minor faction, then their support is not needed). "

I always side with the Legion.
 
They might crucify people, but at least they aren't taxing me.