I have travelled fairly extensively by myself since my husband died 3 years ago and I inherited his ISA account. I have been to Vietnam, Brazil (with my daughter) , Ecuador, the Galapagos, Ireland, Holland, and Spain. These trips are fairly short, usually under 2 weeks.
I went to Oberamagau in 2010 with my husband.
Alta, and others, you do not need a companion. I know it is nicer to have company but lots of single people go. What is good is that these trips have all been escorted so you get into a group and all become quite friendly. I was 78 the other day, and if health permits I would like to go to Italy and maybe Israel this year. Don't hold back! You only regret the things you wanted to do and didn't.