Hi belam79,
Some possibilities closer to the Frederick area are in post #2 here and a few more a bit further away in he Baltimore area are listed in post #2 here.
The Ultimate Dreams is only available online through their Amazon outlet. I don’t know the specific models that the retailers in the lists carry so you would need to call them and ask if they have any latex/polyfoam hybrids on their floor with about 3" of latex over a high quaity polyfoam support core (either with or without polyfoam quilting because either would be helpful as a reference point). I would then visit the ones that carried a mattress that was similar. Many of the manufacturers I’ve listed do make mattresses that are similar but the local retailers may or may not carry them.
The choice between the Eurotop and the Ultra Plush would be a matter of preference depending on whether you feel the advantages of the Eurotop are worth the extra price for you.Post #2 here talks about the differences between them.
Without a reference point of personal testing … I would discuss your firmness choice with Chuck whose suggestions would be based on much better and more specific knowledge of their mattresses than mine. My tendency though would be to choose a firmness choice that you and Chuck believe would suit you best without a topper (which would be on the firmer side because of your higher weight), err slightly on the side of firmness if you are undecided between two options, and then add a topper if you need it based on your actual experience on the mattress when you’ve slept on it. This way if you need a topper at all, you can use your actual experience on the mattress as a guideline for the thickness and type that would be best.
Phoenix