We are planning to put river rock around ours. It is round, and nicer to walk on with bare feet.
Yes, landscaping fabric is a must, or else you will be hand pulling weeds forever. If you are not adverse to chemicals, a good dose of ground clear would not hurt either. You want a ground clearing product, not something like RoundUp. RoundUp works on the PLANT. You spray it, the plants die, and you can re-plant things in the same spot the next day. A ground clear works on the earth. It stayes in the ground and prevents growth for up to a year. Read the lable if you decide to use one, and pick the right kind.
As for bags of rock / marble / etc. Call a masons supply and have it delivered. Unless you are only going to use 5 - 10 bags of rock, having it delivered in bulk, even with a delivery charge is much much much cheaper (same goes for mulch as well) and is a lot less work than getting all of those bags in and out of your car.
As an example, this place in my town has pea gravel at $49.50 a cubic yard + delivery (I think it's $25)
http://www.themulchdepot.com/stone.html
Home Depot is listing pea gravel in bags at $3.48 for a half cubic foot.
There are 27 cubic feet in a cubic yard, so you would need 54 bags, for a total of $188.46 for each yard you need. Plus you get to dirty your car / truck all up.
-dave
-dave