[EricH]

Meh, if men are on Mars at that point, Spirit's probably just about done anyway, as the Earth-based labs that will be studying Mars for a while will be too busy with Martian rocks/soil to take in data from either rover. Bring the rover(s) back, give them their x-year maintenance, and send 'em back out to find more cool stuff on Mars, if they're still in shape for that. (If not, Smithsonian or a NASA museum--driving around.)