I just finished my FIRE spreadsheet! I have made some changes to make it work a bit more generally (ie I won't actually be maxing out my 401(k) or IRA until I have finished saving for my house) It is kind of basic because it doesn't include taxes, yearly changes to annual spending, or inflation. However, you can put in 2 incomes for any number of years and it will automatically allocate money to a 401(k), IRA, HSA, and a post tax account. It also allows you to change the assumed interest rate, employer 401(k) contribution, employer HSA contribution, and annual spending.
I couldn't find anything else like this on the forum (most people are probably far enough along the path to FI that their spreadsheets are much more complex). I've tried to make it clear what all the fields are, but let me know if you have questions. Also, if anyone sees any big problems with the spreadsheet, please let me know!
*Make sure to look at the different tabs so you can at least plug in your 2014 numbers, and check to make sure the assumptions I made are right for you.