Well you have the choice of buying off the shelf from outfitters, going to a cottage mfg for something Ultra light or custom made and some even make their own. The last thing I would worry about is styling. Colors, features ect mean nothing if the pack is uncomfortable. I have learned here to collect ALL the gear you will be hauling for your trip and get a pack that

1 is large enough to carry the gear
2 fits the best when properly fitted
3 is comfortable above all others that you have tried on

That may require you to take a box full of your gear and load up one by one the packs you will be trying on. As others here have suggested maybe call ahead to get some help fitting with someone experienced at a time they don't plan on being too busy. There is no shame in doing it this way and it truly is the best way to get any pack, big or small. Always wait for sales and don't be afraid to ask for a discount at the big retailers. I wouldn't dare ask for discounts from the small custom made in USA guys. They deserve to make a profit so they can continue to make a living.

Ps. ditch those heavy Nalgene bottles and go with some 1 liter soda bottles or something like smart water bottles that come in different sizes. They will both be skinnier and fit in a lot of the small side pockets on the smaller day packs. Not to mention they hold water just as reliably and weigh a ton less.

You may also want to think about hanging things from a pack especially if you are only day hiking. Most day hiking can be done with a smaller load and should not be a problem tucked away in your pack. Things possibly swinging and bouncing around outside the pack unless skillfully lashed can be a real PITA. Always think comfort, lightest weight and don't carry things you will never likely use.

Edit- Oh and by the way, good for you getting into the outdoorsy stuff and helping those scouts. The more you plan for your trips the more fun you will have. So be sure to check out some of the good reading here and ask away if you need help.
jimmyb