Rozzy, I have aliums as part of my seasonal container arrangements. They are going into pots - very belatedly - this very afternoon, after advice received on this site that it's best to plant them now than leave them to rot. Combining the advice I just got on here about flowering times/bulb size and planting depth with the advice I got when I bought them from a reputable nursery, and with what is written on the packs themselves, they will be going at the bottom of my containers, (as the Alium bulbs are the largest, and need to be planted the deepest) with Tulips above them, followed by Daffs, Muscari and topped off with Dwarf Iris. The member of staff/gardener I spoke to knew was looking to plant up containers with a mixture of bulbs for ongoing seasonal interest and she said Aliums would be fine for containers. The Alium bulbs and pack info I have is as follows:
"Allium Aflatunense, cut/dry flower, flowers May/June, height 60cm/24” 15cm/6” deep, 10cm/4” apart, plant from August onwards"
I am by no means an expert, more of a perpetual beginner who learns a little bit more each year, so hope this helps you in some way !