there are not really any swimmable beaches in downtown cabo san lucas proper - the nearest beach is Medano beach, and it's about a 15 min walk to downtown. you can also take a panga over to lovers beach, which is just across the bay - beautiful - just stay on the bay side and not pacific side (which is known as divorce beach - very dangerous rip tides). one close smaller resort would be: www.cabovillasbeachresort.com.
just so you know - it'll be hot in july....., I mean hot.

tener corazón de oro