Balanced money formula

Over the past few months I have not been as ridiculously analytical as I have been when it comes to my budget. I pretty much know that I will spend about $300 on food and $100 on gas each month. What I have been doing which I feel works well is to automatically put the amount of money I want to save immediately in my savings account, and then simply live on the rest.

This is a simple formula and I have been enjoying it. I also feel that I am putting more priorities in my spending this way, just like the book "your money or your life" states.

As for a proper money formula, I recommend Elizabeth Warren's balanced money formula. 50% of your income should go to needs, 30% to wants, and 20% to savings. Some expenses can be considered wants or needs (Do I really need to spend $300 on groceries? I could get by just fine on $200). Other expenses could be considered needs or savings (Is paying the minimum on your credit card all savings, all needs, or a bit of both). However, I feel that if someone can save 20% of the money they make that will give them plenty of options in the future.

Backpacking across the midwest?

Im seriously considering taking a train to Dallas, Oklahoma City, Kansas City, St. Louis, and Chicago then flying back to Austin in early July. The train rides with all the stops to Chicago is about $200 using Amtrak and my AAA discount, and I could fly back to Austin using a southwest voucher I have. If I can find affordable rooms using hostels that should be about $25 a night. The whole trip would probably be about $500.

Any thoughts?