I've walked part of this before but found it much, much more fun on a bike. If you go early in the morning around 7am you can find parking for free in one of the lots close to the Belmont shores side. Make sure you're back by 9am because the ticket police are just waiting to start ticketing and they are pretty aggressive. You can ride right along the ocean, which is really great, to Seaport Village then hang a sharp left along the the embankment where people fish and it takes you around to the coast guard station. I usually take a breather there then ride back. It's so lovely and I've never found it too crowded. You might want to check if there's anything special happening before you go because almost every month there's something exciting going on such as the marathon, Long Beach Grand Prix, sandcastle building, or the annual jazz festival. Catch a cup of coffee on 2nd street afterwards and it's the perfect morning.
A nice level walk along the bay! It's really awesome cause there is a bike path and a path for waking so you don't have to dodge bikes the whole walk. The is a pay parking lot right at the start but if you look you can find free street parking. This is great walk for the family and you don't have to step in sand at any point of you don't want too!
I try to kayak here at least once a month. At $9/hour, the price is very reasonable, and the scenery is great. The water in the bay is usually calm, so it's a great place for first-timers. Scenery is a mix of nature, beaches, boats, and birds as well as houses on Naples Island. It takes about an hour to go around the island, and another 15 minutes to go through the channels within the island. If you're still feeling ambitious afterwards, you can walk the Long Beach walk/bike path down to Shoreline Village and back (10 mi RT).