I did setup the projector on a ladder and figured out the size I wanted - but the wall is green right now so hard to tell what it will look like. The resulting size 'm targeting is what I punched into the calculator at Projector-Central - I landed on 18 fL - so sounds like I should be ok then. Didn't realize the lamp starts to dim as it gets older...just read a post on that.I highly suggest doing this (painting the wall) - it allows you to get a real good feeling for how big to go for a screen size. You can also decide if you prefer 16:9 or 2.35:1.
As far as the calculator, there is another calculator someone linked a while back that is a bit more in depth - I am pretty sure it allows you change the lamp settings. The thing to remember when using the calculator - watch the number of FL. You really want to be in the 12-16 FL range (I stayed toward 16 to allow for lamp degradation).
Thanks for the tips. I'll check out the other calculator this evening.