Mairi, I can concur with the recommendation for Gibson Park. Nice site. Play park next door and there are walkways alongside the Tweed for walking/cycling.
Melrose hardly has a "national" name in the high street. Virtually all the businesses are privately owned. The butcher, baker and greengrocer are first class.
It's a while since I stayed at Glen Nevis so wouldn't like to comment but it is a longer walk into town. It's also a good bit more than two hours from Glasgow.
Likewise, I have only overnighted at Craigie Gdns six years ago so can't give an up-to-date opinion.