My parents have a 1993 Park Ave Ultra and it is like riding on cloud nine as far as a soft ride is concerned. They have the Gran Touring Suspension in it which is a bit stiffer than the Dynaride they had in their 1992 Park Ave Ultra (which they just sold about 1-2 months ago).
The 1997-1998 is pretty much the same when it comes to the roominess, which comes with great abundance.
The Ride quality was improved slightly from what I hear.
The people that bought my 1993 SSE two years ago kept talking about how they loved their 1997 Park Ultra, which had replaced their 1994 Park Avenue (non Ultra). They were buying the SSE from me for their daughter (who backed into a gravity box the first time she drove it, breaking the drivers rear tail lights, damaging the trunk and drivers quarter panel)
P.*. I have noticed that a 1997-1998 Ultra can be had for fairly cheap lately -have seen a few with right around 100k with asking prices in the $4500-$5500 range lately up hear in MN.