What should I bring with me on a 120+ mile bike trip?

I'm planning a trip for for four people on bikes. We'll be going 120 miles over the course of two or three days. What should I bring with us? It'll be a sunny, August day. We aren't sure if we are going to camp out or going to a motel (what are your suggestions?)

Also-- we want the weight to be as light as possible (obviously). So what should we or shouldn't we bring?

- Puncture repair kit (tyre levers, patches, cement)
- Water and energy drink sachets
- Chocolate or some form of energy bar
- Sun-tan lotion
- Sunglasses (not only for the sun, but to keep bugs away and protect you from any grit a car might happen to throw at you)
- Mobile/Cell phone
- Credit/Debit card
- Cash

You might want to invest in puncture resistant tyres like Speciallized Armadillos (6 months without a puncture here :P) and you probably won't need the puncture repair kit.

If you'll be camping, you'll need pannier racks to hold the tent equipment.

Spread tools and other repair parts across the riders. Everyone doesn't need to bring their own tools. You can share.
Sports drink powder that you can mix with water wherever you find it.
To be sure, the packs of protein gel deliver the most nutrition for their size and weight, but I find the taste and texture disgusting. I go for Clif bars instead.
A light rain jacket you can roll up.
A microfiber cloth for cleaning glasses/sunglasses.
Tire levers, two tubes each, and, because it is tiny, the Park glueless patch kit.
A pair of padded shorts and socks for each day.
A jersey for each day.
Sunscreen. Bullfrog gives the most protection for its weight and volume.
Credit card and cell phone.
One CO2 inflator for the group and one cartridge per bike.

HTH

You should definitely stay in motels; the amount of kit you need for camping is very difficult to carry on a bike and is much too heavy. You want a pair of cycling shorts and a few changes of socks and underwear, few T shirts and something a bit warmer for the evenings if it turns cool. Forget any fancy clothes or anything frivolous.