Puerto Vallarta!
Pv is a much better choice than Cabo, IMO. We have been to Cabo twice and now only visit PV every fall and know most of the timeshares, either having stayed there or just hearing about them.
The best areas in PVR to walk around and enjoy are El Centro (downtown and the Malecon Boardwalk) and la Zona Romantica (just south of El Centro with Los Muertos Beach, cobblestones and many restaurants). There are no timeshares in either area, but some are close. To the north, the Sheraton Buganvilias is a great choice. It has a super pool, but no sandy beach due to hurricane Kenna. The beach has little rocks that make a wonderful sound as the waves come in and out. We loved it there and you can walk south to the Malecon and El Centro. Buses and taxis are right at the door.
Our other favorite timeshare is Lindo Mar, which is south of town. LM has its own small sandy beach with rocky outcrops for snorkeling. Lindo Mar is a small boutique type timeshare in traditional Mexican style. You are in your own little universe there, but a cab ride is 50 pesos and the bus is really cheap to Zona Romantica.
Those are the two best timeshaes to me that are semi close to town. Getting into town, both El Centro and Zona Romantica, is what PV is all about.
Further out you can find many other timeshares...especially in the Hotel Zone (Villa del Palmar, Los Tules, Pelicanos and more). We don't like to be that far north, but I know others do like to base from that area. We would never stay as far north as the Marina. But, it all depends on what you want. We like to spend our time in la Zona Romantica and El Centro.
Actually, now we rent a condo at Vista del Sol oceanfront on Los Muertos Beach and then spend a timeshare week at Lindo Mar. The last three years we have been lucky enough to add a week at Ocho Cascadas (once as a trade and twice as a rental). That place is the ultimate!
PM me if you need more info. We are PV lovers!