V6 options

[Necosi]

Hey folks,

I'm in the market for a new daily driver. I'll be buying very soon (called the bank yesterday to check for loan approval and they said the check is in the mail) and have a general idea of what I want, but the newer choices are confusing me a bit. What I'm looking for is a GM V6 that will serve as a daily driver (500 miles a week for work) with a little performance when I want it, not an all-out performer that I'll be driving on a daily basis.

I have owned some of the older Series I & II 3800s and those are actually one of my favorite engines of all time. How do the Series IIIs compare to the 3.5s & 3.6s in terms of throttle response, smoothness, fuel effeciency, potential aftermarket, etc?

I'm trying to keep this below $12k, and ideally I'd like to be closer to 8k. But as I'm putting on 25k/year at the moment, I also want to ensure I get at least 4 good years of service out of it. It seems I can get in a 3.8 for around 8-9k, a 3.5 for 9-10k, but a 3.6 is more like 12-15k.

For instance, here are 2 items that caught my eye in the trader last evening:
'06 Grand Prix 3.8 (NA) 37k
'06 G6 3.5 loaded (I'm assuming that means leather & sunroof?) 60k

I think both were autos, don't have the paper with me at the moment to verify. The G6 has nearly twice the miles, but is actually a little cheaper than the GP. In this instance, which would be the wiser choice in regards to what I'm looking for?

I apologize for any trouble. I tried searching the forums for comparisons between the various options but didn't have much luck.