The thing about Regent is they make any tour free that has a value of "up to" $200.
That means your tour could be worth $49 (a bus and shopping raid) or it could be worth $199 (something a lot more classy).
Obviously, it now appears that the shipboard credit angle gives you a lot more flexibility - as Crystal offers. You could use your $3000 credit for a $500 tour.
Still, of course, nothing is ever free. I am just saying this for the people who like the convenience of not watching their daily budget.
I have been on some truly excellent Silversea tours - from Safaga to Luxor in Egypt comes to mind right now with all the turmoil. An overnight tour with hotel and meals included - wow.
A day in Petra is another one.
One thing to keep in mind with cruise lines that sail to new places all the time, they don't always get the best guides. The lines that stop in the same port week after week get the best guides.