ASTM Guidelines (1292 in particular) recommend using a safety surfacing under and around playground equipment to minimize the risk of falls. Also, in the CPSC Handbook for Playground Safety, there is a chart listing the critical fall heights of different kinds & amounts of safety surfaces that have been tested in accordance with that ASTM Guideline. I've never seen any test results for synthetic turf. If you found a vendor who claimed they had safe synthetic turf surfacing for under & around playgrounds, I'd recommend asking whether it met ASTM Guidelines, and what the critical fall height for it was (the maximum height that the playground above it could attain and still have a kid be safe if they fell to the surfacing). In addition, you may want to inquire about the ADA accesibility of the surfacing.
Rubber does come in different colors that would blend better with the environment. Also, there are border timbers sold by engineered wood fiber manufacturers to keep the surfacing in place when it rains, in addition to drainage systems. Hope this helps!
Synthetic turf is much better if you have the budget - it can run as much as $25 a square foot.
http://www.creativesystems.com