Mike, if you are doing your own mounting and framing, you can really do whatever you would like and feel comfortable with. A 16×24 print, while large, is not impossible to handle, and once the print is secured and framed, it is safe. The handling process is where the extra durability of having the print mounted on mat board or foam core is helpful. I always use acid free foam core as a backing for framed prints (whether the print is dry mounted to it or just mounted using tape, mounting strips, or corners) as it is sturdier than mat board or corrugated cardboard (which some use).

These tips are geared more towards photographers who are selling prints or having their work framed elsewhere. If you frame your own pieces, you can put as much time and care into the process as you want. Custom framers, on the other hand, are usually trying to frame a greater quantity of pieces within a certain time frame. Providing them with more durable, easier to handle prints allows them to work faster and more efficiently, and also acts as extra insurance for your prints when framers are at the end of a long day of framing or under a time crunch and maybe not being as careful as they could be with your work.