Skip the warranty and just open a savings account...you'll be much better off!
And, as mentioned previously...read all the fine print and even try lemon juice to make the invisible ink appear!
If there is a back-out clause in that warranty...use it!
And if they fight you on this then that should be all the reason you need to skip the dealer's extended warranty.
Most of the time the yearly maintenance that they require you to do (whether it is really needed or not) and provide proof that you actually did it will cost you way more than any repairs they may cover if they haven't excluded you out somehow (which they are very good at doing).
And, when you pick it up from the dealer, have them run everything...the furnace, water pump, city water connection, water heater and refrigerator (on both gas and electric), generator (if it has one), flush the toilet...and even have them drain the sewer tanks in front of you!