I've had issues trying to decide on this as well. I'll be going with an almost 4 year old and an almost 2 year old. The younger one will definately need a stroller the whole time, and the older one will walk at times, but will need one too. I decided (after seeing the cost of rentals) to go ahead and purchase two umbrella strollers that do have a cargo bag on the bottom, a nice shade canopy and they also fold up real small and have a strap to help carry them over the shoulder. They also recline!!!!
That is the one we purchased. at 40 bucks, it is cheaper than renting one for $8 a day for 6 days and it's mine to keep and I'll have them at the airport too, if needed (which, knowing my kids, it will be).