SANTA MONICA AND VENICE
I was first introduced to Santa Monica on a family vacation in 1998. Our family stayed at the Wyndham on Colorado Avenue and I remember how cool it was to walk over the 3rd Street Promenade and bike down to Venice. I've returned to Santa Monica several times over the years - many times on a bike ride up the coast from Manhattan Beach. It never gets old seeing the Venice Beach Boardwalk or the Santa Monica Pier. It should feel touristy but it doesn't. There's something about watching tourists enjoy the California beach life that brings excitement. I loved biking along Venice during the Rose Bowl weekend and seeing all the out-of-town Big Ten fans wearing their team colors because Venice is such a contrast from the Midwest and these visitors always seemed to enjoy the new experience.
I've never spent much time on the Santa Monica pier. There's a Bubba Gump for starters and that's usually a red flag to run away from a guaranteed tourist trap.
However I've always liked the area surrounding the pier. I like the huge green yoga area. I like watching people try to go across the swinging rings. One of my favorite places to sit and watch the world go by is the Georgian Hotel. It's the blue building below that looks more like it belongs in Miami than Santa Monica. The Georgian Hotel has a raised patio - which may not sound like a big deal until you consider that every other restaurant along Ocean Avenue has a sidewalk level patio. The three foot raised patio provides ocean views, which you don't get from the sidewalk. I've ordered many a breakfast at the Georgian Hotel followed by several cups of coffee. Three blocks back from Ocean Avenue is the 3rd Street Promenade.
When I lived in Manhattan Beach I used to joke that the worst, boringest weekend I could ever have, when I'd run out of things to do, I could always bike up to Santa Monica. I was being completely facetious about this - my worst weekend counts as everybody else's best weekend. My butt would be a bit sore from biking the windy hour up the coast but seeing Santa Monica and the beach a worthy welcome site.
One thing to know when exploring Santa Monica is that it is a 100,000 person city separate, and distinct, from Los Angeles. There's a lot more to Santa Monica than the beach area and the Third Street Promenade. Santa Monica's Main Street, from around Pico down to Marine, is a great collection of local shops, restaurants, bars, and coffee shops, like Urth Caffe and Grounwork, that remains relatively undiscovered by visitors. There are also decent, albeit more big brand, commercial strips along Montana and Wilshire. 

The photos below are of Randy's Donuts (which is not in the immediate area but I had to drop this photo somewhere) and a mural of Anthony Bourdain around the corner from Snug Harbor, which is a great place for a local breakfast in Santa Monica.
There's always something going on in Venice. There's always something new and changing which makes it a great place to visit because you'll never see the same thing twice. It's a bit hectic and chaotic but that's what you come to Venice for. I'm not a huge fan of the restaurants along the Venice boardwalk but I can always grab a beer and people watch.
It's Venice's recreational areas that I get a kick out of the most. There's the world renowned muscle beach but there's also basketball courts, paddle tennis courts, and skate parks that I think are even more entertaining to watch participants. 
So why is Venice called Venice? Because in 1905 a developer named Abbott Kinney built a bunch of canals to make this part of southern California resemble Venice, Italy. The canals sit off the beach on the other side of Pacific Avenue and if you didn't know they were here, it's unlikely that you'd accidentally stumble upon them. I missed the canals on several previous visits but now try to walk through whenever I'm in the area.
A Forbe's Magazine article called Venice's Abbott Kinney Boulevard the "Coolest Street in America" (which could have immediately made the street uncool). Like Santa Monica's Main Street, Abbott Kinney sits a bit off the main drag and remains undiscovered by the larger Venice boardwalk tourist crowd. The clothing boutiques are a bit funkier. There's an Intelligentsia Coffee in the center of the commercial district. I also think the dining scene is of a slightly higher grade than Santa Monica - I always have a good meal at Gjelina.