Knitters - Circular needles help please!

[Ceolas]

I am going to knit this cardigan for DD1.

I need 4.5mm and 5mm long circular needles for doing the sleeves and the rib.

As far as I can see, they come in different lengths: 30, 40, 60, 80 and 100cm.

What length should I get?

As far as I can see, you're not going to be doing anything actually in the round, just using them as long needles essentially, so I would get as long as you can bear. I would have thought that 80cm would do probably. You could always treat yourself to a set of Denises, and then you will never have this dilemma

those Denises look sort of cool, but I like bamboo!