Agreed, however in this context, the Miranda is more accurately equivalent to the Nebula, which at least has something similar to the large, primary bay of the Galaxy-class, and possibly at least one bay in the aft "pillar".
I'm not entirely sure that that is a useful distinction, as Age of Sail "cruising vessels" (from which the term originates), were the exploratory and long-range workhorse designs of their era.
However, it's what we've got.
Suggestions that I have come across:
Springfield class is a larger science ship, that is, larger than an Oberth.
Cheyenne is a lite explorer.
I think that Challenger design might be a frigate.
I don't know what to make of the Freedom class.
I once emailed Rob Legato about the original battle footage from "Emissary" that ultimately went unused. I asked him if there was ever a model built for the Apollo class U.S.S. Gage that was mentioned in a previous version of the script. Both he (and later Michael Okuda) mentioned that no new models were built for the scene, but that old models and model wreckage that was available were used, such as the damaged Reliant from TWOK. Apparently there was also old wreckage that he added the name "U.S.S. Tolstoy" to, but until that footage is ever seen, it will remain a mystery.
The Renegade and the Thomas Paine (both listed as New Orleans class ships in the Encyclopedia) were mentioned in dialogue as being frigates, so the Kyushu was probably a frigate as well. Greg Jein obviously took cues from Franz Joseph's Starfleet Technical Manual when building the Freedom class Firebrand and the Niagara class Princeton, as the former ship resembles an updated Saladin/Hermes scout/destroyer, and the latter ship resembles the Federation dreadnought with three nacelles. I'm not saying that's what the ships are, but the similarities are unmistakable. The Cheyenne is also obviously an update to the Constellation class explorer, and the Springfield and Challenger classes are also probably science/exploration vessels as well. The Nebula is a capltal ship like the Galaxy class.
I like a lot of what I read here. I like the idea that perhaps Starfleet uses the configuration for overall classes of ship, but updates the components to new generations. So, trying to fit Sternbach's "explorer, cruiser, cargo carrier, tanker surveyor and scout," I fit the classes into two generations, based on whether they have pens for nacelles or Galaxy-style nacelles.
cruiser-The Niagara could be a dreadnought with its 3 nacelles, but I am listing in under cruiser here, to fit Sternbach's system. The Cheyenne has four nacelles, replacing the Constellation (and probably the 4-nacelled Excelsior prototype), so it would be lighter cruiser. The New Orleans, with 2 nacelles, looks like a cruiser in most Trek eras, but is perhaps called a frigate because that is similar but implies it is smaller than the Galaxy.
cargo carrier-The Freedom-class has only a single nacelle, but it has a very large saucer like the Galaxy with an even larger shuttlebay, so I suspect it's a carrier.
tanker-I could concede the Nebula as being enough like the Miranda to match that in its era. The best argument for that is the "Proto-Nebula" variations that show it can be configured for different uses like the Miranda was. I list under tanker since the similar Ptolemy and "Antares?" classes could carry cargo pods, and some publications claim the Nebula could carry a cargo pod, though that was not shown onscreen that I know of.
surveyor-?? unknown, but Merced (built but not shown on screen) and Norway (the ship with the most Galaxy-like nacelles from First Contact) are possibilites, depending on how old they actually are.
scout-The Springfield looks like an Oberth (nacelles on top, pod on bottom, no neck), so it is the new science vessel/scout. The Challenger resembles the Hermes, so it would also be a scout.
I like the idea that the "Explorer" is a new type of ship for TNG that is huge enough to basically be almost like a base that can move, with families, more labs, etc. Really, the Ambassador was big enough to be this, too, but it is called a cruiser in Yesterday's Enterprise, so I can accept that Starfleet did not choose to use that name until the Galaxy class. Really "Explorer" is probably a peacetime way to not-say-battleship.
It seems that there would be a few cruiser/frigate "sizes" at a time, with more dedicated and specific designs in the other classes.