Hi Avik:
[quote]Just got my Leesa after having only slept on coil mattresses my entire life (I am 41).
Im finding the mattress quite firm and very hot.[/quote]
You can see some of my comments about the Leesa mattress here.
It’s not really possible to quantify the sleeping temperature of a mattress for any particular person with any real accuracy because there are so many variables involved including the type of mattress protector and the sheets and bedding that you use (which in many cases can have just as significant an effect on sleeping temperature as the type of foam in a mattress) and on where you are in the “oven to iceberg” range and because there is no standardized testing for temperature regulation with different combinations of materials … there is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here that can help you choose the types of materials and components that are most likely to keep you in a comfortable temperature range.
In very general terms … the materials, layers, and components of a sleeping system that are closer to your skin will have a bigger effect on airflow, moisture transport, and temperature regulation than materials, layers, and components that are further away from your skin and softer mattresses or foam toppers will tend to be more “insulating” and for some people can sleep warmer than firmer versions of the same material.
There will be a break in and adjustment period for any new mattress or sleeping system as the mattress loses any of its “false firmness” and the cover stretches and loosens a little and the materials settle and your body gets used to a sleeping surface that is different from what it is used to (see post #3 here). This could typically be a few weeks but it can be shorter or longer depending on the specifics of the person and the mattress (higher density materials can take longer) and it can be surprising to some people how much their sleeping experience can change over the course of the first few weeks.
I would be cautious about using other people’s comments as a reference point for your decisions. Only you can feel what you feel, and that is the most important thing. You didn’t mention exactly how long you’ve had your mattress, but it seems that you’ve had it a short time. You chose a mattress with a 100 day trial period, so that is a good thing. I certainly would try to give the mattress some time to adjust to you, and for you to adjust to the new mattress. Give it at least 30 days, as most people tend to have a pretty good idea within that time frame and it allows the mattress to lose a bit of its artificial “stiffness” when new. It is true that memory foam does tend to sleep a bit “hotter” than traditional foams/mattresses, and that may become an issue for you.
While it’s not possible to make specific suggestions because of all the many variables involved that are unique to each person and your own experience is the only way to know for certain whether any mattress/topper combination will be a good “match” for you in terms of PPP, the first place I would start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that you will need to know how to make the best possible choices … and know how and why to avoid the worst ones. One of the links there is this article about the types of manufacturers or retailers that I would look for.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort” and PPP (Posture and alignment, Pressure relief, and Personal preferences) that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for when you sleep on it in “real life” and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability and PPP (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists (based on all the parts of your personal value equation that are most important to you).
[quote]The only two I know of thus far that seem to have solid reviews are Brooklyn Bedding and Plush.
I have however read that a number of people have had customer service issues with BB.[/quote]
Please see my comments above regarding reliance upon “reviews”. There certainly are many quality mattress manufacturers out of the 500 or so in the United States.
Brooklyn Bedding is a member of this site, which means I think highly of them and their products. Customer service issues aren’t something that we’ve found a lot of commentary upon here at the site, but if you’re considering one of their mattresses then the best thing to do would be to place a phone call to them and discuss any concerns you might have regarding anything you’ve read. I know they’d be happy to address any of your potential concerns.
I look forward to hear about your progress and what you decide to do. 
Phoenix