I've seen a lot of "Wealth Projection" spreadsheets on here, and to me (maybe Excel OCD) they look messy.
I tend not to get so into the weeds on projecting my spending. I've got a running total on Mint.com and actively track my average monthly/yearly expenses from our family (Including mortgage, we're looking at $55k right now, in a high COL area. Room for improvement, sure, I'm just giving it as an example).
Tracking my expenses loosely, and conforming to as many frugal tendencies as my wife can put up with, leads me to focus more on projecting my
savings and investments. I like to estimate how much we'll stash away in a 401k based on the previous near-past, as well as Roth IRA contributions and Taxable Account contributions.
I mostly invest in Vanguard funds, and don't have any investment properties (just a primary residence). So, using a spreadsheet to forecast the future is practical.
Here is a link to a GoogleDocs version of the Excel spreadsheet I use. If you want to use it, save off a copy and fill in the assumptions page. This is a generalized look at things, and you can tailor the end result page to fit your needs (Example: As it stands, my wife might completely stop working for 3-4 years when we have our 2nd kid, then come back to work. I can delete out a few years of her salary on the projection page). The biggest part of the assumptions page is whether you want Today's dollars or Future Dollars. I like to use Today's dollars, because I don't like trying to figure out on the fly whether or not $1M is a lot of money in 30 years.
Criticism is welcome. I'm just showing how I do things.
https://docs.google.com/spreadsheet/ccc?key=0AnZCadE3qiVNdGJxeHpvYlNxU0lKUjA3aFJDbzJOWEENote: I put in generic numbers in the assumptions page. While it's pretty easy to find my financial info on these forums, I didn't feel like having it in GoogleDocs.