I said yesterday that part of my problem with time-travel might come from the stories I've read that involve it. When I started to think about those, it reminded me of kalinara's comments and Scipio's post on differences between Marvel and DC, and their preferences for DC. And perhaps not surprisingly, time travel pretty accurately reflects what they said. I'll give you a minute to go read what they wrote. Go ahead, I'll wait.
You done? No? Geez, how slow are you?
Finally! See, I noticed that in Marvel, the future always sucks. Like Scip said, DC is about inspiring, that you can make things better, whereas Marvel seems to push more of an inevitability that things will turn out poorly, no matter how hard you try. Also as kalinara hypothesized, DC heroes of the future work with authority, whereas Marvel characters are always in a difficult struggle against whatever authority there is.
Example: DC's 30th century to Marvel's. The Legion seems to have been generally liked and respected over their many reboots. I know that in my dad's books from the 1960s, they're beloved. Even in the most recent series, they may have started out as enemies of the establishment, but eventually they were able to gain acceptance and join the fold. Their members are people from different worlds, each possessing some power inherent ot their race, and they're people who chose to leave home and join the Legion. On the whole, their time seems pretty nice. It looks clean, and peaceful (except for supervillains, but that's what the Legion is for, right?).
Contrast that with the Guardians of the Galaxy. Again, a group composed of people from different worlds (all from within our Solar System if I recall), but now they're the only ones left. The Badoon have wiped out everyone else from their worlds, and they have no other choice but to fight. For other races, the future may be OK, but for the protagonists it's pretty lousy. Or Marvel 2099. A somewhat dirty looking world, dominated by corporations that still try to destroy mutants, when not experimenting on them. Where people addict employees to drugs just to keep them in line.
Booster Gold came from the future to gain financial independence. The future in general wasn't bad, just his in particular. Contrast that to every time-traveler in Marvel history. It's always about preventing some awful future, where heroes are pretty much all wiped out, and the rest are desperately just trying to hang on. While the plan of a Cable, Bishop, or Rachael Summers is certainly more noble than Booster's, it gets pretty depressing when you consider these people keep coming to the "present" to fix things, and yet never manage to change anything.
Maybe it's just that I've been reading the Marvel stuff for so long, it feels stale. Maybe I've played too many video games set in apocalyptic (or post-apocalyptic, or barely pre-apocalyptic) times. God knows it got tiring watching the constant "change the future" attempts on the X-Men cartoon. It's not like the characters are bad because they're time travelers, that simply can't be the only thing about them. When Marvel worked off of Bishop's history as a member of the XSE and made him a cop in District X, that was interesting. I thought Impulse was pretty cool and until that Teen Titans/Legion crossover, I had no idea he was from the 30th century. It never seemed like a big deal in terms of his character, though maybe that would change if I read his series.
Man, I can't believe I'm agreeing with Scipio. It's a good thing I beat Phantom Dust today, or that might depress me. ;) Augh! I used an emoticon!! It's the end of the world!!! Run from the Sentinels!!!! Start up the time-matrix, we have to stop my past self from beating Phantom Dust, so that I'll be too depressed to use an emoticon!!!!! OK, I'll just stop now.