I'm currently in Shetland enjoying a mix of weather from idyllically sunny to driving rain - often in the same hour. I love it in both moods and all the stages in between. It's no hardship that a wilder kind of day is a good excuse to go to Lerwick to enjoy both the museums and the wool shops. It's a heady mix of inspiration for a knitter.
Working on the principle that someone out there might find this useful this is my idea of a good time - you could start at either end!
Shetland Textile Museum. If this is open it's more than worth the £3 entry fee. Exhibitions change each year and sometimes within the season. This year one of the rooms is devoted to the late Zena Thomson, she taught me to knit at primary school, she was a brilliant teacher and a formidable knitting talent, it's been a real treat to see so much of her work together. The textile museum shop is also brilliant and you don't have to pay just to go in that bit (do pay!).
There can't be many gift shops where the things for sale can match the quality of some of the exhibits - there's a nice selection of yarn from some of the smaller organic producers, these are at the more expensive end so it's great to be able to see them before committing. The knitwear is always inspiring, and there's generally people demonstrating upstairs who will teach a little and give useful advice.
From the Textile museum it's a short hop to the The Woolbrokers (Jamieson and Smith) on the North Road. It's the bigger of the two dedicated yarn shops and they've been really good at introducing new ranges/weights of yarn over the last few years. The heritage ranges, and the 1 ply cobweb lace yarn are interesting, and so is the latest 5 ply sports weight they do. There's an excellent choice of colors in jumper weight too, but the biggest draw from my point of view is the extensive range of yarn they have on cones - 250g for the new 5ply, 500g for everything else and a few 1kg cones in stock at the moment.
Cones are the cheapest way to buy and the savings can be significant, they're perfect for larger projects - jumpers and shawls, as there are no ends to tie in either. they're oiled for machine use so you need to be thorough when washing and dressing your finished piece, and you'll get grubby hands knitting, but when you find a colour you love they're an excellent investment.
Next stop would be the Shetland Museum at Hay's Dock. They also have a decent collection of historic knitwear (as well as a cafe and toilets). From a knitwear point of view, their displays don't change as much as the Textile museums do, there are some star pieces there that are well worth repeat visits.
From the museum, it's a pleasant walk into the centre of the old town (10 minutes at most) on a dry day. The Peerie Shop, Loose Ends, Ninian, R.A.M, Anderson & Co, all have a good range of knitwear to have a look at. Loose Ends sells Uradale Yarn and a couple of other smaller local producers. Ninian and the Peerie Shop are great for Shetland themed gifts of all sorts.
As you go along Commercial Street there's probably my favourite shop, fabulous windows, Jamiesons's of Shetland I love the heathered colours they produce and their famous wall of wool. They produce their yarn in a wool mill at Sandness so everything happens in Shetland, and there's also a decent range of machine-knitted jumpers, slip overs, cardigans, and hoodies as well as a few tweed items for sale alongside other gift type things. Both Jamieson's and the Woolbrokers do a good range of pattern books (the Woolbrokers possibly have the slightly better collection of these). The staff in both shops are also great with advice for every knitters level and can help with everything from required yardage, through colour matching, to shipping if you want to buy a lot.
Jamiesons have the best range of Double Knitting weight and if you want coloured lace weight this is probably the best place to look. Spindrift and jumper weight are interchangeable between here and the woolbrokers - there does seem to be an amount of personal preference between more experienced knitters but I don't have one. If the bands are gone I can tell the difference based on colour with reasonable success, but not on texture or quality. You can get everything here from a really fine lace weight through to a super chunky Arran weight.
The Shetland Times bookshop is definitely worth a visit too - there's a good range of knitting books, both Shetland specific and beyond, an excellent selection of more general Shetland books, and plenty more besides.