"There should be a family of HLLV's, perhaps. With the smallest version capable of putting 30 tonnes in LEO and the heaviest 150 tonnes (just guessing)."

If the market for launch vehicles doesn't change, those vehicles capable of +20 tons of lift to LEO may be too big. If were to actually open the space frontier, we could get rockets with +1000 tonnes capacity of payload to LEO. As for the projected govt projects of exploring the Moon, Mars and/or elsewhere with manned crew, the currently available hvy lift rockets can be used for this- there is no reason why we need to build a rocket which can repeat what the Saturn V did: having one rocket which can lift enough so that everything needed to land a crew to the moon and return safely is on that launch vehicle.
With gas stations in space [such as in LEO, in L-1, and on lunar surface] with one crew launch from Earth using existing hvy lift capacity you could get more payload to the lunar surface and back, than if you had a Saturn V [which had 4-5 times the lift capacity of current hvy lift]. Add gas stations to Mars' surface and orbit and you can also do a manned Mars.
Or let's say that you are under the delusion of assuming that only a govt can build gas stations in space, and therefore because of cost concerns of a govt running a gas stations, you don't want a dozen or so gas stations in space, but were limited to just one gas station. If this one gas station were put on the Lunar suface. Roughly speaking, you would effectively double the existing lift capacity from Earth (as far as getting crew to the moon or *even* beyond {it would be better to have a gas station at L-1 for getting beyond the Moon- to Mars, asterioids, mercury, etc}).
With commerical gas stations in space, one can get more gas stations and cheaper rocket fuel and more importantly unlimited quantities at some knowable and somewhat dependable future price. With cheaper rocket fuel in space [and by cheaper I mean prices of somewhere around $2000 per lb or less {especially if higher volume is sold}] one transforms space into a true space frontier. An example is if you have enough fuel in LEO and it's cheap enough, one can change the type of vehicle needed to return to Earth- instead of re-entering at around 9 km/sec, you could re-enter at half this speed.
Using chemical rocket fuel in the space frontier, probably will be similar to using horses to open the American frontier. We could have those "painted" solar sails using beamed energy (might work really well launching from the Moon) and could also have space elevators, tethered orbital assit thingys, mass drivers, fusion drive, or whatever. But we can use the "horse" and may continue using the "horse" even when at a point in time when people are riding a beam to Saturn.