I agree with your thoughts here. I generally up-vote all my posts as I am investing my time and the rewards are not so great. Since I value my time I up-vote my posts. If I start getting higher rewards for my posts then I might consider not upvoting myself.
Regarding comments I am flexible. I generally upvote my comments in two scenarios
- When I need my comments to be visible.
- When I have spent time on creating long posts (something on the lines of a post) I upvote my comments. I refrain myself from voting smaller comments I make. When I upvote my comments I also try to upvote atleast one other comment which has added value to the discussion.