Hi gerberasai,
I’m assuming that the guidelines you have read are the ones in Post #2 here and the topics it links to which have more information about mattresses and children and “safe” materials including a link to some general guidelines for children in post #2 here. It also includes a number of links to the better forum posts and topics about mattress and children as well which have more information about many good mattress choices for children.
Since a 2 year old doesn’t have the ability to provide any meaningful feedback about which mattress is best for them for most parents testing a mattress in person is often less important because any sleeping surface that is in a medium to medium firm range and that uses materials that are “safe enough” would be suitable for a child.
The first step in choosing a mattress for a child is to use the guidelines about “how safe is safe enough for me” to decide on which materials and components you are most comfortable with.
I personally think that some combination of latex, natural fibers, and innersprings can all make good choices for a child and if a lower budget choice is a major consideration then polyfoam that is CertiPUR certified can also make a good lower budget choice as well but just like buying clothes for your children or deciding on the type of diet you feed them and are most comfortable with this would be a choice based on the parent’s “best judgement” and their lifestyle choices. A latex comfort layer is also a very durable choice so a mattress that uses it can maintain its initial comfort and support well into their teen years and would still be in good enough condition to add a topper as they grow and develop more adult proportions if they need some additional softness and pressure relief to extend the useful life of the mattress.
In your case how suitable the mattress is for you is also a bigger consideration that will affect your choice and in this case I would be a little bit cautious because a mattress that would be soft enough for many adult’s preferences may be too soft for a child and I would prioritize the needs of your child over your own.
If edge support is important to you for when you sit on the edge of the mattress for “story time” or even for the times when you sleep on their mattress then I would make sure that you test any mattress you are considering to make sure that the edges are “firm enough” for you either when you sit on them or when you lie down on the mattress in the area that you would normally sleep in. If a latex mattress isn’t firm enough for you on the edge then an innerspring that has specific edge support may be worth adding to your criteria since latex mattresses don’t normally have (or need) edge support (see post #4 here for some comments about a latex mattress for a child and edge support).
Once you have decided on the specific materials you are comfortable with then it’s just a matter of starting the process of narrowing down your options from there based on the criteria that are most important to you (including your testing) along with budgetary and lifestyle considerations because there are so many mattresses that would be a suitable choice for a child that your own criteria and preferences will be the only way to choose between them.
If you are only looking at local options then post #2 here includes the better options or possibilities I’m aware of in the Washington, DC area but I would suggest checking their websites and calling to talk with them first before you visit to make sure that they carry a mattress on their floor that meets all the criteria that are important to you in terms of materials, budget, and edge support.
Phoenix