Michael,
I mulch all my beds with 3-4" of cypress mulch with very good success. Many others on this board use a variety of different types, but the main advantages for using mulch is the moisture retention in the summer, added insulation in winter, and weed suppression. The reason I use cypress is alot of my beds are around my pool area and the cypress does not "float" like other mulches, it is a bit more bug resistant, cypress does not need replacing as often, and I personally like the look of it. Mulch in general has many advantages, but I also think it really dresses up a bed better than not using any... IMHO...
