Personally i like kapaa it’s a small town but it has some very nice resorts and very good shopping. Also i would recommend going to a travel agency they can help you find cheap condos for rent on kauai. And by the way poipu beach is beautiful.

The north side of the island (Hanalei Bay) is often cloudy and rainy.
The south side (Poipu) is sunny most of the time.

Poipu is fantastic. Brenekie beach has some good snorkeling, but if you go a few minutes west you can swim with the sea turtles (don’t touch or harrass them though – huge fines).
On the north side of the island there are some great spots for snorkeling. You can pay to go on a Napali coast snorkeling tour boat. I didn’t do it, but heard that it’s just amazing.
You can rent the gear at almost any spot on the island. Most hotels have them. The condo we had in Poipu had a closet full of beach gear; straw mats, masks/fins, boogie boards, surf boards, and even bikes. Shop around. Here is the link to the Poipu Kai Resort condos
They are very nice.

Poipu is the most popular place to stay but everyone is there. It can get pretty crowded.
Yogi Berra once said, “Nobody goes there anymore, it’s too crowded.”

The Princeville area is nicer but more expensive. The Marriott near the airport is my favorite spot. It’s centrally located and has beautiful grounds to wander around. It is the site of the old Four Seasons Resort that was destroyed by hurricane Nikki in 1997. Marriott took it over and refurbished everything.

If you’re a golfer, stay away from the Princeville courses. You’ll have more fun at all the other courses. If you don’t take this advise and play one of the Princeville courses, you can apologize later.

There is a great set of hiking trails north of Princeville and worth the adventure. It is 4 miles to a beautiful waterfall. The trail meanders along a small stream that you wade across 11 times. It is shallow and cool and very beautiful. Take lots of water to drink and a picnic lunch.

Poipu is very popular but you can find less crowded beaches up Kapaa way. Definitely search for a condo via vrbo, it is worth the effort of going through their lists.

You don’t need to go to the extra expense of renting a jeep, an ordinary car is good enough. Kauai is probably the most beautiful of all the Islands but it isn’t nearly as busy as Maui or Oahu. It is also more humid there.

Be sure to take in the Smith’s boat tour up to the Fern Grotto and if you want one of the best luau experiences in the Islands, Kauai has got a couple to choose from.

Poipu is best because it’s the sunny side of the island. There are plenty of things to do, some great hotels to visit, and nice restaurants to go eat at.

There is a great beach right there for snorkeling, however you don’t want to miss Kee Beach at the end of the road on the North side of the island. It’s the best for snorkeling and you can’t miss it, literally it is at the end of the road.