In a barley wine it's more to balance out the malt flavour. I've made a couple of barley wines before and not used enough bittering hops and the flavour has been a bit overpowering. It's not to get hoppy flavours in there like an APA, but more of a balance.
Back to yeast, I realise my last comment wasn't that helpful. I've made two American barleywines before and used US-05 and MJ44 California Ale yeast, I think both can ferment up to 15%, far higher than either of my BW were. However, if you're looking for a more traditional BW then an English ale yeast would be best. When I'm finding a new yeast, I like to go on to my favourite HBS and read the difference between the yeast styles and find which ones have the best characteristics for my beer.
So if I was making a barley wine, I'd go onto GEB and see which English ale yeasts they have. I'd read their descriptions and see which ones are best for the flavours I'm going for, the FG I'm aiming for etc. For me, I usually make a choice early on whether I want dry or liquid yeast. For liquid yeast a starter will be necessary and I'd spend more time getting the fermentation temperatures right. For dry yeast, if the OG is >1080 or so I'd recommend buying two packets and rehydrating them.