Talk about blockbusters! This is a tough one...
Ok, first for the easy part: I would definitely pick up Kendall for Bennett. No contest: if he's healthy and gets his confidence back, he'll outperform Bennett by a lot. I like Gibbons, too, as well as Kearns as a keeper, but neither justifies dropping someone from your team.
Maybe I should just quit now while I'm ahead... Oh well, here goes:
Your lineup is stacked, no matter which version you look at (ok, that was still easy). One thing I would try before deciding on either of these deals is whether you can somehow upgrade at 2b - Reese is your weakest link at the moment, and improvement there would be worth more than reshuffling already powerful positions.
The main factor is your scoring. If you're playing roto, especially 4x4, Cedeno may be nearly impossible for you to deal without getting speed in return. In points leagues these trades probably look a lot better.
The other factor is position eligibility. In general, I disagree with cwebb about Nevin being a significant upgrade over Glaus, but if you can play Nevin at first, you've gained quite a bit of insurance. Any of these lineups should be at or near the top of their leagues, but on injury or two could change that quickly. The more positions you can back up, the better off you are.
Bottom line: if losing steals won't kill you, I like trade number one. Trade number two helps you position-wise, but you're not getting quite enough in return: Garciaparra vs. Jeter is principally a matter of taste, and Jones isn't enough in return for Glaus. if you can negotiate your way to a 2b upgrade as part of this one, it makes a lot more sense.
Hope this helps. Let us know the specifics of your league, though - we may be missing something here.