The first time I was out on any type of trails in years I had a tire on the front very similar to that Kenda and it was ok and did better than expected since the trails were more rough than I thought they would be. If I would have had one on the back it would have been better than the more narrow tire I had. If I was using the bike for your purpose a pair of those would work fine IMO.

A few days ago there was a thread with a few posting this tire from Nashbaras the best you can get especially for the price for what you are wanting. They said it rolled pretty good lasted pretty much forever and the priceis tough to beat.

http://www.nashbar.com/bikes/Product...2_10000_202470

For me I just like having some extra width in general and then anything offroad I just want more. If you are just going off the beaten path I don't think you need anything very aggressive, but I am a very aggressive rider no matter where I ride.