Hi GSW408,
The first place I would start when you are looking for a new mattress is post #1 here which has all the basic information, steps, and guidelines you will need to make good choices in terms of quality, value, and suitability.
The “right” choice is very different for each person and depends on budget, body type, sleeping style, and preferences and many other variables. while Dreamfoam / Brooklyn Bedding is a manufacturing member of the site and among the best quality/value for its budget range … no matter what the quality or value of a mattress … it may be perfect for one person and completely unsuitable for the next. Post #2 here has more about what the “right” choice may be for each person.
If you are looking at an online option that you can’t test in person first … then I would make sure you talk with them and also test local mattresses that may have a similar “feel” so that you have an idea of whether the specific design would be suitable for you. In the case of the 13" gel memory foam … they have said that it is similar in “feel” to the Tempurpedic Cloud Luxe but just a little firmer so it would make sense to do some good testing on the Cloud Luxe first to make sure that it is suitable for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). A forum search on Ultimate Dreams 13" (you can just click this) will also bring up more information and feedback from other forum members as well.
Some of the better options and possibilities I’m aware of in the San Jose area are listed in post #2 here.
Phoenix