Hi Athan.
Welcome to our Mattress Forum 
all the way from Spain! I was able to understand your post just fine no worries.
If the forums you were reading were, as you suggested, not mattress-specific, I would be hesitant to trust them as a source as their goal is likely affiliate sales.
Have you tried a Sheraton Hotel Bed before? I would caution against making a decision based on other people’s reviews, as what one person feels and enjoys on a mattress can be very different than what you may need and prefer. If you haven’t already, I would suggest taking a look at our Mattress Shopping Guidelines. It is our suggestion that people stay away from major brands.
I have taken a look at the Sheraton Hotel Bed. It appears to be an innerspring mattress with a pillow top. Unfortunately, specific information about this mattress was impossible to find (the thickness of the comfort layer, the materials in the comfort layer, information about the pocketed coils). Without this information, and without knowing your BMI (height/weight) and sleeping positions, it’s hard for me to make a meaningful comment about this mattress.
“Hotel mattresses” tend to be lower quality and value than the consumer mattresses made by the same manufacturer in the same price range and more basic versions of the retails products that many mattress companies offer (which isn’t a good thing). One of the “secrets” to many hotel mattress is that they usually use a bedding package that includes a mattress pad or topper that is a big part of how the mattress feels and can also add to the durability of the mattress (replacing a mattress pad or topper can be less costly than replacing a whole mattress because a mattress or sleeping system will usually soften or break down from the top-down). In many cases the more subjective short term experience of sleeping at a hotel is an improvement over the mattress that people sleep on regularly and this often “translates” into the perception that hotel mattresses are better than they are. They are a frequent source of buyer’s remorse. They tend to be firmer products using softer “top-of-bed” materials to create extra plushness. There’s more good information about hotel mattresses in post #3 here.
It would appear the Sweet Bed by Ibis is a mattress made of polyfoam. The danger with polyfoam is that it can often be a “weak link” in a mattress – depending on your BMI and the density of the material, it may break down rather quickly. Our Mattress Durability Guidelines talks more about this. Again, without knowing your BMI and the density of the polyfoam in this mattress, it would be hard for me to make a meaningful comment.
I was able to find some better specifications for the Simmons “Feeling Firm” Mattress.
30 cm height
Sensoft Evolution® firm suspension
Sensoft Evolution® Ultime springs
Aquasens batting (150 gr / m2)
Quallofil Allerban® batting (300 gr/m2)
Biosens cover
Elivéa® 4 cm, density 43 kg / m3 (2.5 lb/ft3)
Firm foam 1.7 cm, density 22 kg / m3 (1.3 lb/ft3)
There is not much information available about their Sensoft or Elivea technologies/materials and I was also unable to see more about the coil count, gauge, or thickness of but the spring unit is rarely the weak link in a mattress. The foam density looks adequate, assuming you are within a normal BMI.
I was unable to find a resource that breaks down the layers in the Sealy Illinois mattress. If you are able to find those specifications and share them with me, I’d be happy to make a comment on this mattress.
We do recommend that consumers seek a local retailer or manufacturers that are transparent about what is in their mattresses. See the how to find a great mattress outlet article here. When assessing any product, also be sure that you find out information listed here so you can compare the quality of the materials and components to the mattress durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
The Astral Nature mattresses are using high-quality materials. Are you considering the Nerva specifically?
Also, along with any mattress specifications you find, let us know what you are looking for in a mattress. What is your height and weight? What is your sleeping position? It will be much easier to comment There are many variables involved in making a good mattress purchase decision… so don’t feel tempted to rush it.
Phoenix