Grif: It sounds to me like you should look at a "Z" style riding mower - the Z stands for zero turning radius so you can mow around all kinds of obstacles in the turf. Most every manufacturer makes one: John Deere, Cub Cadet, Toro, Exmark, Scag, Walker, etc. I like Exmark for value, we use their 21" mowers where I work (Superintendent of Grounds at the UCD Medical Center) along with 72" John Deere 935 riding mowers (expensive to buy and maintain) and we mulch all year round at the highest cutting height. Go to your local commercial mower shops and check out what they have in Z riding mowers and see what they recommend. Some even provide test rides! I'll be interested to know what you end up with.
No longer president, River City Beemers
2009 R1200RT - Silver
"Shadowboxing the apocalypse, wandering the land"