Don't put $ down if you have excellent credit. You won't recover it if the car is totaled. Keep the money in your bank account, much safer. I always do sign and drive leases, never write a check. Keep my cash in the market where it's making me $.
This is a good calculator:
http://www.bankrate.com/calculators/...alculator.aspx
Once you find the residual/MF (interest), you will know about how much you should be paying. You can find the residual/MF numbers on Edmunds's forums.
FYI, I'm doing $335/month (incl 6.2% tax) with $0 down 15k/miles a year on a '12 Sonata Limited 2.0T ($30K MSRP, gross cap cost was $25k after rebates/discounts).
Lexus and Infiniti has good 27 month leases (over 70% residual) that you should also look into. Payment will be over $400 though.