Now I've extracted the Truvativ Giga Pipe Team SL Bottom Bracket from by Trek Pilot after 10 years of use. The question is do I just replace it with the same thing and reuse the original Bontrager select cranks? Is there an easy upgrade? This was my main bike but I'm becoming more of a multi bike person so I don't think this will see any more 300 mile years. Since I have some classics I need to invest in and then I'm looking at eventually getting one nice new bike as well I feel like just sticking with the same parts makes the most sense.

Ask yourself two questions:
1. Is there anything wrong with the existing BB?
2. What do you want in the way of a BB and crank?

If the crankset's in decent shape and you're not looking to change it for some functional reason like a different gearing range, I'd just replace the bottom bracket (if it's worn out) and be done with it. Truvativ Giga Pipe Team SL bottom brackets are still available and aren't terribly expensive ($30-40), so you could get an exact replacement. Or you could opt for a different ISIS bottom bracket with the right threading and spindle length if you wanted to spend more or less. Nashbar sells a house-branded ISIS bottom bracket for $23.99 if you want to go the bargain basement route.

Let's see, you got 10 years out of it and you plan to ride it less per year now so it would not be unreasonable to expect another 10 years or probably more for $30-40. Sounds like a decent deal to me. How much better do you expect an upgrade is going to be?