I think much depends on your specific area. Do many of the other homes have both or is it a mix. I think many people are getting away from the need for a tub if the rest of the home is awesome.

Does your condominium community appeal to empty-nesters, working couple without children or starter families? Most empty- nester buyers appreciate low clearance access to bathing/showering rather than stepping over high tub sides. That being said, walk-in soaking tubs with showering capability have become desirable and can also satisfy the starter family need for a bathing situation for children. A fast-paced working couple would appreciate a good sized shower with some bells and whistles...multi-function shower head, personal hand shower...speaker for news or music, etc.

Good considerations. I'm on a golf course with weekend renters, not long term. Most owners are retired or near and use the condos for holidays away from the city. My interest is to rent the condo and use temporarily, then sell when the market returns. I'm leaning toward a shallow tub 19". The shower would not be larger than the standard 60x30" size anyway. Other units have jacuzzi tubs for relaxation. I couldn't afford to go there.

I suggest you reconsider the tub. Kohler makes a terrific acrylic shower pan with integral seat (32"x60") from the Tresham Suite of products.
http://www.us.kohler.com/us/3-Shower-Refresh-Ideas/content/CNT19000034.htm
Combine that with a tiled wall, semi-frameless clear glass sliding shower door, multi-function shower head, good looking towel/grab bars and you have bathing that will be attractive to your market. These items are all available at Home Depot.