There are lots of options available for villas on the island. Read the "Plantations" sticky above the forum to get a sense of each before you book. I would not hesitate too long to book as many villas are already reserved for the entire summer. For close beach access, Palmetto Dunes, Sea Pines and Shipyard are your best bests for plantations; villas in the forest beach area are also good options, as well as around Folley Field (like Hilton Head Beach and Tennis resort). You can also read reviews of villa properties under the "vacation rentals" subject line on the upper left side of the forum page.
Golfing in the summer months should be planned early in the day as it gets quite hot and humid here in August. When I play, I tee off by 7:30 AM. There are lots of courses on and off the island, many of which will have some summer specials- these are often advertised in the island Packet newspaper in the sports section. I have never had a problem getting a tee time in the summer.
If you are not bringing your own bikes, there are many bike rental companies on the island that do pick up and deliver to your villa. They are competitive, so shop around,. Many offer discounts if you book at least 2 weeks in advance. Just do a "google" search and most companies will pop up.
Hope this helps. Once you have narrowed down your villa search, feel free to post again if you want specific comments about those on your list.
Edited: 10:15 am, March 06, 2013