Please suggest current resources for designing UX for senior adults. W3C standards documents are about 6 years out of date.
With respect to navigation on tablet devices: are menu bars preferred or an array of icons?
Here are a few resources:
There are also a few questions on Quora(.com) that address this issue; search for 'core UX concerns'.
In general, older people take longer to use computer technology, and need simpler designs. Make your UIs simple and have plenty of space, don't squash things in; avoid complex controls where possible; include accessibility options, and use a reasonable contrast in your colour scheme.
In respect to navigation: err on the side of simplicity. Words are easier to understand than pictures so menu bars may be better; on the other hand, icons are also a good visual aid so you might want to consider some small icons alongside.