I love Pampers Swaddlers and Pampers Cruisers. They are just soft and stretchy and cute, plus you can record points on their website for rewards (toys, books, etc.). Luvs gave my daughter a rash. Having said that though, I plan on trying some cheaper brands with this next one because if there is no rash problem I'd rather save the money.
At a few baby showers I've been to, the host has mentioned in the invite that each guest could bring a small package of diapers and be entered for a door prize drawing. It was optional, but people usually bring a couple of different brands and sizes that you can try out with the new baby. I always thought it was fun. But the door prizes should be something good since diapers are expensive and they are usually going above and beyond the original gift.
Also, the Wal-mart website sometimes offers free diaper samples. There's a Huggies one out there today but they change them frequently: http://walmart.triaddigital.com/Free-Samples.aspx. You could start getting some now and then you'll have a few samples to try when baby gets here.
HTH!