Worldmark vs Wyndham Oceanside: based on your comments, I suspect you might be better off with Wyndham.
The WM is north of the river. Walking from there to the pier is possible, but not all that pleasant. You could certainly uber/lyft it, but why not stay where you want to be?
The WM is between the railroad tracks and the freeway so noise is an issue. The units are good sized and comfortable, but bring your earplugs.
You walk down through a separate parking lot, through a tunnel under the RR tracks to the Harbor. Left past some small shops to sand and right around the harbor to watch the boats. Keep going and you will end up at Marina Inn; VI (Vacation International) has some units there. It's right on the tip of the harbor for fabulous views of the boats coming in and out etc.
Wyndham: is right by the pier. If you want to walk the pier/beach/shops in town, this is the spot. The train to San Diego would be easier to access with the stations just a couple blocks away. The RR tracks are in back so those units will have noise. We stayed on the other side and could hear the train as well. The train tracks are an issue anywhere along the coast, so take that into consideration.
For San Diego stays, as a WM owner, I used Oceanside as a day or two stay to tide me over between exchanges. Mostly, I preferred to stay at the Four Seasons in Carlsbad or even the Welk/Hyatt in Escondido (back when I could get a 2 BR there for a couple hundred bucks with the old XYZ program, but I digress about the good old days...). FSA isn't on the beach, but it was very comfortable and the trains are too far away to wake you up. We were always there in Jan/Feb when there was plenty of availability. Also, traffic on I-5 between Oceanside and San Diego is awful. Check the trains to see if they run when you want, or just look at one of the San Diego resorts and be where you want to be rather than sit in traffic etc.
You also mentioned Pagosa Springs. Most of that inventory is Wyndham. They dumped some lesser units into WM and have remodeled some, but Wyndham is the better option for that location as well.