I climbed Aspiring via 'the ramp' (the easiest route) some time ago. We climbed it in late summer and the actual climbing was largely rock scrambling once we got off the Bonar glacier. We didn't use any gear except being roped up on the glacier. If you are looking for a more 'alpine' experience on the ramp route then I'd suggest climbing earlier in the summer season (e.g. December) when there is more snow rather than later (e.g. Feb). The South-West ridge also looks an incredible line, but obviously harder and not something I've tried.
While you are in the area, the ridiculously named Mt Barff is also a fairly easy and enjoyable climb - especially in early season when there is (or was back when I was there) a sweet ice colouir down low leading onto the main ridge.