Round-Country Road Trip Cost?

Any insight into important things to consider and overall cost of a road trip across the country and back? We (just two of us) would be starting in eastern PA (where we live), then taking a central route so we can see some of the national parks out west (most likely the CO/UT vicinity), see Yosemite, then going to San Francisco (prob stay in a hostel we know of). After that, we want to head south and hit up LA and San Diego, then head into AZ to see the Grand Canyon and petrified forest. We want to see stuff in TX, most likely San Antonio. Then we wish to stop by New Orleans and do do a couple days worth of volunteer work, then eventually getting to FL and using Amtrak reward points towards taking the Auto Train up to VA (as far as it goes) and returning to PA. That’s just a very general outline. We would like to keep costs as low as possible, possibly some camping here and there. We’re driving an AUDI A6 Avant, so plenty of storage space and comfy ride. Takes premium gas though.

Here are some ways to save money and still enjoy the trip:
Stay in motels during the week, rather than on weekends, generally they are cheaper then (exception is some large cities with a lot of business travelers).
Eat breakfast out, it tends to be the least expensive, and keep a cooler in your car with salad, sandwich items, fruit, and drinks. You could take a gas barbecue with you have treat yourself to steaks, burgers and whatever by utilizing city or county parks, rest areas or even outside at a motel, and certainly at camping areas.
If you don’t have reservations in advance, plan to stop traveling by 3 – 5 pm.
If you are doing some camping, having an easy to put up and take down tent is a plus, and having your car arranged for maximum ease of packing and unpacking will save a lot of stress!

To figure gas costs, Do a rough estimate of the miles you will travel, add 20% to that, then multiply by the max amount of the cost of gas (see http://www.gasbuddy.com ). If you are traveling in summer, be aware gas costs are generally more, so plan accordingly.

Motel costs will avg $45-85 depending on location. In some places you will pay upwards of $100 or more if it is a busy weekend, or special events are on. Campground costs avg $12-25 a night for most places, more if it is a campsite in an RV Park.

Have a great time! Sounds wonderful!!