Hi antRI,
The Tempurpedic cloud uses a combination of 4 and 5 lb memory foam which is mid to good quality/durability but you are also at the borderline where I would be little cautious of using 4 lb memory foam, especially in thicker layers. Of course the Tempurpedic is also poor value compared to other similar quality memory foam mattresses with similar configurations.
The Vinyasa is also a poor value IMO and worse yet you would be sleeping on 3" of polyfoam rather than latex. You can read a little more about the Vinyasa in post #3 here.
The Thera-Foam is a polyfoam support layer so these would be a latex/polyfoam hybrid. Good quality polyfoam (or an innerspring) with a latex comfort layer can be a good choice for those who are not in the budget range of an all latex mattress. In this case … knowing the density of the polyfoam base is important (it should be 1.8 lbs and up) so I called them and they will check with the factory about the density and they will email me the answer (probably tomorrow) and I’ll post it here for future reference.They don’t carry all latex mattresses although some of the Therapedic licensees across the country do.
As you probably know … these are both members of this site and I think very highly of them and consider them to be among the best quality/value and service in the country. The members that specialize in online or “on the phone” help and guidance for their customers and ship across the country are also very good at making layering recommendations.
There are some general guidelines about body type here and about different sleeping positions here and a section that talks about how different types of construction and layering can affect both of these guidelines in this section but these are general guidelines only and may not apply to any specific individual. All 3 of these interact together along with every other component of the mattress and the person sleeping on it and with the many variables between different people and mattress constructions it wouldn’t be possible for me to provide more specific recommendations without much more lengthy and detailed conversations on the phone.
The good news though is that there are two ways to find the more specific layering and recommendations that have the best chance to work for your unique circumstances …
The first of these and the most accurate is local testing on a mattress with the help and guidance of an “expert” that has the experience and knowledge to help you make your best choices for your particular needs and preferences.
The second is with more extensive conversations with an online manufacturer who knows every detail of the mattresses they make or sell (not just the foam basics) and how each of their options interact with different people. With good feedback about any local testing you have done in combination with “averages” and a customer base which would include customers that were similar to you … they can be surprisingly accurate and this can go a long way to reducing the risk of an online purchase and making more “accurate” choices.
With all the unknown variables and without a reference point of customer feedback on specific mattresses and knowledge of every mattress component and layer in a mattress you are considering, any recommendations I could make would not be nearly as accurate as either of these two methods in helping you make your best choices.
The most effective source of specific recommendations is always always to “connect” with the people who make and sell a mattress you are considering and work with them to use their knowledge and experience to your advantage rather than trying to learn all the variables you would need to know and risk becoming overwhelmed and frustrated with the process of designing or choosing your own mattress based on what I call “theory at a distance”.
Hope this helps 
Phoenix