I have used a stocks and shares ISA for quite a few years for investment rather than saving for a rainy day accounts and had very good returns, obviously goes up and down but generally over the long term it has out performed any other account i have ever held.
Although now at mid 60s i am trying to spend money rather than save at my time of life. My IFA said once you are aged 60-80 you need to stop saving and start spending any large lump sums you have. You obviously need a pot for emergencies but generally you need less to live on as you get older and can spend more on the good things for yourself.
Tried Premium bonds but didn’t have a great return, the only benefit i suppose is that if you have maxed out all other tax free products and you will get hit with any return on your tax threshold then its better than nothing.