Perhaps I'm too influenced by science fiction books and stories, but Titan seems to be a nice choice. There is also a really cool concept of using high density of Venus atmosphere to make buoyant colony-balloons according to this pop-sci but a 'good long read' article.
Absolutely. There are a crap load of moons in this solar system that we could go play on. Titan, given it's atmosphere and geology may give us an approximate look at what early Earth might have been like. Europa likely has a freaking ocean under all that water ice. Who knows what else is basically in our own back yard that we haven't discovered yet?
Part of me wonders how cost effective these kinds of experiments would be, but the other part of me says "Fuxk budgets! It's for science!" So do I think Titan and Venus are practical? Hell no. Do I wanna see something like that happen anyway? You bet your shit I do.
Well, until tried and explored we will not know for certain if there are no benefits indeed. We are already getting to a point where mining Moon for Helium is starting to look cost-effective. Who knows if within the next fifty years the cheapest rubber or plastics will not come from Venus, perhaps steel or some of similar composite metals could be best created on Mars when supplied in infrastructure. Plus I have a similar "Fuxk budget! It's for science!" mindset, you are unlikely to get a criticism of the idea from me :D.