Tire recommendations for wife's GS

245/50-16 are a REAL NICE upgrade. Slight difference in overall height, which will affect your speedo slightly (1.7 mph at 60 on my GTP i think). But, handles like an f-body and looks a lot better.
Michelin tires are the best money can buy IMO. Especially for general use. X-Ones are awesome all season runners, very quiet, and long lasting.
I put Yokohama Avid T4s on my Park Avenue Ultra and they are great. Stock size, handles way better and ride is quiter and softer than the OE tires.

Cheaper than Michelins too, which are also great tires.