In April we had a Lincoln Towncar (Signature Limited). We've had these a number of times with Dollar. The other one we often get is a Chrysler 300.
The 300 is a fairly recent addition to the Chrysler family, so more modern in appearance (albeit retro styling). The Lincoln Towncar is a bit old-fashioned, but much better build quality and definitely more luxurious.
Both are fully-loaded with leather interiors, automatic seats, good sound systems, etc. A 300 would cost somewhere in the low $30s (although when we dropped our car off in May, we did see a 300 Hemi in the Alamo lot - that would be cool). The Towncar Limited probably starts at around $45K.