I liked them both, I kind of wish they had stuck with base building in DOW2 but they were both good in their own right. I have also been looking at Saints Row 2 for a while now, and so the deal really benefits me. If it has some decent length missions for a campaign I think it'll be worth it, because the campaign of RTS games is usually my favorite part. I also play last stand quite a bit with a friend, so the new units could add some fun.
I am also pleased that they are going the expansion route than selling bits and pieces as DLC.
Avoid Saints Row 2, It's a good enough game, but it's been poorly optimized on the PC. Horrendus frame rates especially while driving even on high end systems that are well above the Reccomended specs. With the right setup, you could minimize it, but on most systems the stutter actually makes some of the missions close to impossible,
Plus Volition (Who ported it) has no intention of dealing with the problem, they made an official announcement a while back (Once the reports started coming in of the poor optimization) that they wouldn't be supporting the PC version any longer and at the time were ruthlessly locking and deleting any threads on the official forums that even mentioned the problems or asked about one more patch.