Leiden is a lovely city, a boat trip on the canals, museums aplenty (Naturalis with some excellent huge dinosaur skeletons, Corpus for a trip through the human body, museum Volkenkunde has amazing exhibits for instance).
Leiden-info.com has info on the nightlife and restaurants etc. Contact them to see if they have an english version of the website
An hours drive is Edwin van Huik's bassconnection in Hilversum http://www.connectionbult.com/wp/
Excellent shop
Bax has shops in Amsterdam, Rotterdam, and Goes. Not bass specific though.
There's plenty more to see and do in Leiden https://www.visitleiden.nl/en/plan-your-visit/information/tourist-information-centre
And most other citys are 30-60 minutes away by train. By car, avoid driving between 7-9am and 5-6pm.
Enjoy!