It depends. If you are using mortar then thinner would be better but if you are using sand and then planting in the cracks thinker 1 1/2-2" would be better. Anyone can do anything it depends how much stamina you possess or how impatient you get. Your soil base determines if you use a base of gravel or sand. Gravel is more stable, sand is less. You probably will not be having frost heaves so it depends on how hard you want to work. Lots of labor involved and mortaring can become messy and removing it from the stone. I would go with a 3" gravel base then 2" of sand. 30 X 12 is a huge undertaking. Wear gloves.

Here is a link that might be useful: Propagating Perennials

Thanks for the reply. Let me ask, if we were to hire it out would you still say 3" of gravel and then 2" of sand? Or would you pour a mortar base? I guess, what is the best?

Also, do yo uhave any idea how many tons of 1.5-2" rock covers (and/or how much 1" covers)?

Thanks again