yep you sure can
overall I really like the developer points as there are many things you CAN do
--you can rent to help offset some of the initial cost
--you can use them for an extra vacation or a longer vacation
--you can upgrade to a larger room that you normally dont have enough points for
--you can bank your regular points(or a portion of) and use your developer points for the current year. I like this option a lot for those who may not be buying quite enough points to cover their entire trip every year.
or you can do several of the above
we went with 2 extra days than normla for our spring trip this year AND we are going with a larger room for our fall vacation