I used a double strap carry - stand bag for years. Had to buy a little canvas Sunday bag at Prestwick when my clubs didn't arrive on my flight. I dug that bag out again due to the new baggage rules and used it all fall in Finland. Even with 14 clubs and being 50 and a bad knee, I had no problem walking. However, if I get a blister, I might want a cart, but otherwise, I'm a convert.
JC, taking exception to your statement that all modern courses are designed as cart courses. I think many of us, while trying to accomodate the fact that carts will be an option, do not design in such a manner that allows that fact to take precidence over our design tennants. In fact, I don't even think of or refer to them as "Cart Paths". To me, they are service roads for maintenance. I don't specify that the course purchase golf carts. If they do so on their own and let those carts drive on the service roads - that's up to them. However, I will try to intregrate them into the mozaic of the terrain in the lest visually offensive way possible. So, to me, carts are a management issue, not a design isssue.