There is a good article in this month's (March, 04) Lawn & Landscape magazine regarding cemetary bids. You may find it on their website www.lawnandlandscape.com.
Cemetaries, and churches for that matter, could be hell to service. Older, esp. historic cemetaries, can be physically tough as graves have sunk, aisles between headstones are too small for anything but a trimmer. Churches are tough if they hold a good deal of community meetings or activities.
When you're under the gun, it's hard when you show up to provide service and you've got a girlscout troop playing on the front lawn - for the fourth day in a row.
On the other hand, smaller country churches can be great. Enjoyable, peaceful, beautiful surroundings, nice clients. Low activity.
Try to anticipate any problem you might encounter, physically and logistically. Go for it, but be realistic.
Cemetaries can be great training grounds for maintenance. I started by using my small push mower because I was too afraid to bring out the heavy equipment and cause any damage. I now, two years later, use my 48" walk behind with a ride-along velke in fourth gear. It works, although you may find yourself in some unique yoga poses trying to weave in and out of obstacles.