Traditional Afro-Cuban tumbaos for son styles at their simplest comprise just four notes per clave phrase, but they must be well placed. A well played tumbao is unobtrusive in its support of both piano or guitar and conga - noticed least when present, noticed most by its absence. This one observation highlights the power of the bass in conveying its message, the groove, at near-subliminal levels when it is as much felt as it is heard.
With acoustic bass instruments, it's simply a matter of physics. The lower frequencies have longer wavelengths and require larger resonating surfaces. The ideal would be the acoustic double bass, which would be flexible enough to be played pizzicato or bowed for the older genres like the danzón. Its surfaces could be played with the finger and thumb joints for percussive accents. There are few acoustic bass guitars that could get into the same region, and the best I've come across is the Guild B30E.
Then there's the electric upright or bass guitar; more portable, less fragile, and a plethora to choose from. I would tend towards a 5-string over a 4-string if my hands were large enough.
What to play
Recommended tumbaos to start with are (in order):
Two of the most useful pointers I received when I started playing Latin bass were:
Salsa Guidebook For Piano & Ensemble by Rebeca Mauleón. (External link)
The True Cuban Bass by Carlos Del Puerto & Silvio Vergara. From the same people who brought you "101 Montunos". A well planned book, the link is to the book and CD package. (External link)
The Latin Bass Book: A Practical Guide by Oscar Stagnaro & Chuck Sher. This is a weighty tome and must be the definitive work on playing Latin bass. (External link)
& Merengue Society