If you haven't seen them yet, take a look at Caesar Miniatures for example, as they currently do a very nice range of figures including orcs, goblins, elves, dwarves, undead, and 'adventurers' - though their elves do have large anime style ears that need trimming down/off in my opinion, and the cartoony nature of their orc and goblin miniatures may not be for everyone (note that a closer look at what's in each box can be found at the Plastic Soldier Review website).
Well, as I say, I've been painting a few of these figures recently (with the aim of using them in a future AoS campaign) and they have proved to be really nice figures to paint:
Unlike lots of regular sized (28-32mm) figures they are not overburdened with too many odds and ends (so that's less fiddly things to mess around with for a start), and they don't (for the most part) suffer from some of the wacky armour and oversized weapon designs that some larger figures do.
But you don't have to limit yourself to these 'fantasy' figures as there are tons of historic medieval/dark-age miniatures out there at the same scale which work just as well.
A 1/72 scale Zvezda viking pictured next to a Caesar dwarf and elf
And, if like me, you're not a fan of the 'warhammery' look of the Caesar orcs then there is an alternative in the form of Orion/Dark Alliance orcs (additional pics of some of the orcs can be found on the Plastic General blog).
A Caesar skeleton and wraith/spirit pictured next to a Dark Alliance orc
I've also found that in some instances, figures from other scales can be perfectly suitable too ...for example pictured below is a 15mm minotaur (from Magister Militum), an old GamesWorkshop skink, and a 'Zahranian Verman' from Black Tree Design.
Another problem I sometimes face with 'regular' sized miniatures is that I often find the prospect of painting larger monsters a little daunting (I don't know why - I just don't like painting them very much). But at this scale a 28/32mm orc model is the perfect size for a troll ...as shown below:
An Italeri barbarian next to a Ral Partha 'Gargantua' orc (based on a 2p)
But obviously, not all monsters are humanoid, and since I'm looking to (eventually) cover all the monsters in the AoS book I've also found the following miniatures that are suitable for wolves/direwolves and giant spiders.
A 15mm wolf (minus its rider), and a 10mm giant warwolf (both from Pendraken Miniatures)
An old GamesWorkshop plastic spider, and a smaller spider from Black Tree Design's 'swarm'
So to sum things up I think that gaming in 1:72 scale is perfectly doable - so long as you're willing to work with a limited monster palette (or are prepared to search through a lot of miniatures websites). It's probably also worth pointing out that most of the plastic 1:72 box sets contain around 30 miniatures for less money than what you would pay for a single metal figure in a high-street wargames store.