If you are fairly sure you can win, always go for it. If you aren't sure if you can win and the worst that can happen is you are forced to draw, always go for it. If you aren't sure you can win and you may be defeated/let someone else win, it's a toss up if you should try or not.

I tend to view draws as a reasonable way to end a game amongst friends, and I also see a three-way draw as more stable than a two-way draw for obvious reasons. Usually if I see myself lagging and don't see a quick avenue to a big SC advantage, I'll lobby for a three-way draw with other players. Anything more than three and I need special consideration, such as a five-way draw I pulled off on another website where I managed to take a dominating FG alliance and build a stalemate line out of the last remaining Italian army located in Sevastopol, and then a mixture of Austrian and Turkish forces to build everything out. The Italian army was absolutely necessary to establish the stalemate line, so he survived to see the end despite losing all his home SCs and being down to one army.

Otherwise, play for the solo.

In truth, I try to make these decision by about 1902, and by then it's usually pretty obvious whether you have a good chance at the solo or not.

If I'm in a game where another player can definitely win, but chooses to draw, I'd have mixed feelings.

If I was in the draw I would certainly not feel like I earned it. (Sure there is the whole, if you can talk him into it, you earned it, thing, but that's pretty thin IMHO.)

If I was eliminated, but had tried to help that player win, in revenge against other players, I'd be pretty damn pissed.

Taking a 3 way draw instead of a win would not make me feel like I could trust you any more. It might even have a negative impact since I disagree with the decision.