Ok, I just wanted to let everyone know how I got things settled on this issue. It seems that the Adventure series is being discontinued. I wanted to try the 6 or 7 but never got a chance to. I settled on the Lowepro Orion(also discontinued) which is almost identical but a little lighter than the Tamrac. I chose this because it is one of the smallest backpacks I could find at the lowest price and still had a place to carry a tripod. I am not really fond of the material on the back, but it is ok. Besides, this is the one that my husband will most likely carry on our trips because I will be carrying two cameras with me at all times.
But I also ordered the Smoky Mountain backpack by F-Stop Gear and I love it. It is really well made and the most comfortable of any camera backpack. It is an old school backpack that does not resemble a camera pack at all. It is not designed to carry a tripod but is perfect for just a day trip in the city or country. The only negative thing I can say is that you have to flip up the zipper flap in order to get the zipper to glide more efficiently, but that isn't really a big deal. I noticed that when I bought this item it was only one of the three color choices that were available and they had just dropped the price slightly. I hope that is not an indication that it will be discontinued, because it really is an awesome bag. One of my favorite landscape photographers, Patrick Di Fruscia, uses their bags and loves them, so I think they are a great company. Their products are just not something that most of the retailers carry.
And last night I happened to be in the sporting goods department of Walmart and found an insulated backpack for carrying cans of beer, it was only $9.00 and with a little bit of padding from the insulation it is perfect to just throw a camera in there for a quick trip to the garden, it is really small and light. What a steal! So I guess I am set for a while on the backpacks. Thanks for all your advice!