For Steem active users, I would have just used the number of accounts active in the last 7 days, which is currently approximately 6000.
Also, no need to leave off transfers and votes from the transactions per day. Today there were:
- Transfers per day: 1,061
- Votes per day: 30,058
- Posts + Replies + Edits per day: 7,323
Totaling approximately 38,000 transactions today (not counting other transactions like POW, market activity, and a few other transaction types).
Good points, for some reason I couldn't find the votes and transfers per day stat.