Darn. Wish I saw this in RecFam! Love to support that corner of things. Usually pretty quiet though..

Any way...

I ride with my wife. I tow my toddler in a seat or trailer. I ride on the street and on the bike path and on the easy kind of MTB trails (BTW, a "29er" IS a full-on MTB to do your worst on). I have been riding again for about three years now, I recon. I used all of the possible comutations of the above situations to buy a whole bunch of stuff. Let me save you some time and trouble

Get a cross bike.

If you are doing enthusiast level riding in ANY of those situations a cross bike will take care of you just fine. If you really get into and one way of riding you might need a MTB (which you have) or a road bike (ditto). For any thing else a cross bike can not be beat for comfort, durability, speed, or utility. I finally bought one a month ago and it is every thing that I ever heard any one rant about cross bikes being and more.



*edit: Sorry. You have a Trek 730! Looks to me that you already HAVE a bike capable of every thing that you mentioned. The "29er" of it's day. If you just want to get a new bike then get whatever blows your skirt up the highest. After all, it;s the bike that you LIKE the most that you will RIDE the most!