great sketches! it is not a long time ago I made a post like this about my drawings wrom vacation in Grece..... they are not as good as yours, I used only pencil, but you inspired me for the next time :)
https://steemit.com/travel/@marty-arts/holiday-without-sketchbook-never-thassos-greece
Awesome! Definitely give pen a shot and just feel free to make mistakes. Let me know how it goes.