A good car seat, stroller, and crib are mandatory. Since these will probably already be covered with grandparents help, I highly recommend a swing.
I do not have suggestions on brand, style, etc. My baby is almost 11, and I was thrilled with the open-top swing, which was relatively new back then. My daughter did not like her bouncy seat much.
I suggest getting the swing, maybe a bouncy seat and nursery monitor, and some of the small items mentioned. One of my very favorite things was an
infant gown. These are unisex, made kind of like a dress, with an elastic/open bottom. So quick for middle-of-the-night diaper changes! Also a
baby wipes warmer. It's a heating pad that wraps around the wipes container so they aren't so cold on baby's bottom.
You generally get lots of newborn and 3-month size baby clothes, that I generally buy bigger sizes. This is very useful for when your baby outgrows everything (which happens quickly) and you don't have lots of $$$. Anything left, I would put on a gift card to ToysRUs/
Walmart/Target/etc. so they can buy diapers, formula, or whatever else they need. Babies can be choosy -- My daughter was bottle fed, and she liked exactly ONE kind of silicone nipple on her bottles and pacifier. Also, Pampers & Luvs fit her well, but Huggies tabs rubbed on her waist and just didn't fit as well around her legs. I liked Huggies wipes the best, because they felt really soft and weren't too wet or sudsy.
It is also nice to make a casserole and send over.