Quite a few gooduns in West Wales:
Llanelli - Cefneithin past Swiss Valley reservoir with views of the Gwendraeth Valley. Connects the flat Millenium Coast Path with an abundance of rural hilly options further North.
Gowerton - Blackpill connects a current railway station village with Swansea seafront & onto Mumbles. Difficult to ride past the Railway Inn at Killay.
Neyland Marina - Haverfordwest. Pretty trail at the Western end of Brunel's line to a Ferry/Liner terminal. Loads of wildlife and great onward options along quiet lanes from Haverfordwest.