I've vaped mainly unflavoured for about 2 years now and I also use a high % PG. I started DIYing about 3-4 months in and thought I should try unflavoured to get an idea of what it was like as a base before I started adding flavours and loved it so just stuck with it. Now I very occasionally add a couple of drops of premix - any more and it is far too overpowering. I have realised I really, really like the taste of nicotine - any nicotine I've tried has been good - it has a kind of fizzy taste to me. I've did try without nicotine or flavour and didn't like it so I intend to stay with nicotine long term. Currently on 8-9mg in the main (some 3-6 when testing new tanks/ builds). I dropped from 28mg and have no intention of dropping any lower (but I have said that before). Before I tried it I thought it would be tasteless but it definitely isn't. What is actually really interesting is when I tell (new to vaping) people I am vaping unflavoured nearly all of them assume it's a tobacco flavour before they try it (and everyone who tries it likes it). I think it's good for first timers as they get an idea of vaping without tasting a flavour that they don't like putting them off. In the UK quite a few online places sell small (30ml) bottles of unflavoured in the DIY section - I buy big bottles at 72/74mg (the highest you can get legally in the UK) and then mix with PG and a drop of VG in a big jug and re-bottle - really simple. No B&M's near me sell unflavoured though and the real pain is when there are deals online with free ejuice thrown in they don't offer an unflavoured option
Maybe a B&M that do their own mixing might sell you a little sample bottle to try?)