Should I keep my regular phone?

Question

Or should I go completely wireless?

Answer 1

Only you know the correct answer to that question.  It is only a matter of personal choice and circumstances.

Answer 2

In my opinion, yes.  Cells can be useful if there's an electrical failure; landlines can be useful if something happens to the cell towers or the cell's connection.

Plus, if you have an emergency at home and need 911, your landline will immediately identify your location.  Unless you have Vonage.