Just returned from 5 nights in an overwater villas on the north/west side of the island. In case there are any snorkelers looking for advice, I wanted to share some information and recommendations.

1. The house reef is very nice and exceeded our expectations! My wife and I saw lots of turtles, eagle/sting rays, black tip reef sharks, octopi and all kinds of incredibly beautiful fish.
2. If you ask the lifeguards, they can advise on the best time of day to head out to the reef. It typically coincided with low-tide and lower wind.
3. If you are a strong snorkeler, the best way to access the house reef is to walk down the boardwalk for the north/west over water villas. As you pass villa 231, there is ladder down to the water. Swim parallel to the villas and out towards the darker water and orange buoys. You will know you have reached the reef when you see the depth drop significantly (from ~8 ft deep to ~50 ft or more).
4. Once you reach the reef, swim east (to the right) tracing the edge of the drop-off. We saw countless schools of fish, a few harmless black tip reef sharks, and a couple turtles.
5. Eventually, you will reach a point where the reef ends and there will be sections of sand and sea grass (follow the buoys). This was the best place for us to find turtles and eagle rays. On one of the days, we went before breakfast ~8 AM, and there were at least 10 turtles.
6. You aren't allowed to swim into the area where the dive center is located, so you should plan to swim to shore around the Turquoise restaurant. (note: there is a nice reef section between the rock wall and the entry for the harbor with the dive center, but you'll have to swim back west to exit near Turquoise, which made the swim back to shore a lot harder. Maybe we just got unlucky with the current that day, but my wife made it clear she didn't want to repeat that part of the swim on our later snorkeling sessions)
7. If you are not a confident swimmer/snorkeler, the dive center has organized trips where they take people out to the house reef by boat with a guide. We did not do this personally, but it seemed like a good option.

One other spot that we found very good was under the over water villas on the south/east side of the island.

1. You will want to talk to the lifeguards about the best time to go here. The current can get quite strong during high tide, and low tide can be VERY shallow.
2. This is where we saw several octopi. They are VERY good at hiding and camouflage, so you have to look carefully. They seemed to be more active towards the later afternoon, but that might have just been our luck. The lifeguards may be able to give you hints on the last place they were seen.
3. You can swim in from the beach or there are ladders down from the boardwalk. We saw 3 octopi near the big piling next to the 2nd ladder.

Last notes:

1. We brought our own snorkel gear. The dive shop appeared to have nice gear, but we did not use it.
2. When we arrived in late December, the dive shop said we were past the main manta ray season. I believe that ended around October/November.
3. We combined our trip with another resort (Outrigger) in the South Ari Atoll, where they have whale sharks year round. There are no guarantees, but we got lucky and had the chance to swim with a whale shark. It was amazing, and I highly recommend it.
4. If you want to do more than one resort in the Maldives, you are probably going to need to fly back to Male and pay for two sea plane trips.
5. If/when we return, we are going to try to time a combo trip with the whale sharks and manta rays in Hanifaru Bay (May - November).

Hopefully this helps all the snorkelers make the most of their time at Le Meridien! Thanks to all the other posters for their advice on rooms and food/beverage packages. It helped us make the most of our trip.