Though it would most likely be a pipedream, I do agree with one of the above posters: Bring back an updated Apollo. If not the actual launch vehicles themselves, use the same concept. It worked incredibly well. The Apollo CM
/SM, by its nature, was highly adaptable to a range of missions (exactly what we'd be looking for). It could fit happily on two different launch vehicles, carry (limited) payload, etc.
Put Launch Complex 39 out of its misery, make it a historical site, give up-close-and-indoors tours, and leave it. Has anyone seen the pictures of the VAB after all the hurricanes? That's some serious damage on top of what was already done. Oh, and of course put a Columbia memorial on 39A and a Challenger memorial on 39B.
God, to see a Saturn V (or equivalent) going into space...can't even begin to imagine what a sight that'd be. Heck, can't even imagine what a sight it was back then. That sucker was HUGE.
With all the technological advances we've made in the past thirty years, we could make MAJOR improvements to the design. I'm even sure we could come up with some way to make some of the components reusable.