I'm sure either of those mentioned will hold all the caches you will ever use on the trip. I wouldn't spend a lot of money as one never knows what kind of accident you can have on the trail. I know from experience,ask Beachcomber.One day a couple of winters ago I had a brand new Zire 71 that I got off ebay and even spent way over $100 for that one and it was toast after I fell on it. I managed to get another one just like it for a lot less and have had that one ever since. With the new caches along a route feature on GC.com you should be able to find out where all the caches are within said distance of the route you will be traveling. I would check out Ebay,you can buy some great PDA's for less than 50 bux. Sounds like a great trip and have fun.