I know Rick recommends the Liechwedd Slate Caverns tour in his guide book and it is also included in his North Wales video, but just heard from a relative of a relative who lives in Conway that it's not so great. I am planning to lead a family tour there next summer and wondering if anyone has been there recently and can report on it. Thanks!
I took the slate mine tour in 2013. If the weather is good, I would not do it. It's okay and slightly interesting, but can't compare to the scenery in the area. I also took the coal mine tour (Big Pit) which was further west. That one was excellent. I learned a lot and our tour guide (a former miner) was funny and fascinating. That one was worthwhile, but I wouldn't do the slate mine tour unless it's pouring rain and you have nothing else to do. Just my two cents.
Correction - The Big Pit is further east, not west. I can't remember the name of the town.
It is actually "Llechwedd Slate Caverns", with a double L at the beginning. Website: http://www.llechwedd-slate-caverns.co.uk/
LL is a common way to start place names in Welsh, for example in the famous name "Llanfairpwllgwyngyllgogerychwyrndrobwyllllantysiliogogogoch". Don't try to pronounce the LL, it is virtually impossible for English speakers, it sounds like a cross between 'CL' and 'TH'!
We went on a tour of the Llechweld slate mine and found it to be very interesting and informative, probably because of the historical importance of the industry. I suppose the level of interest or attraction it would have for one is proportional to one's interest in history. We enjoyed it, but it's understandable that it might not be everyone's cup of tea.
Thank you all for your input. And I did realize it had Ll at the beginning--just missed it. We have family ties in the mid-Wales region and will actually be spending quite a bit of time in the vacinity and will have numerous opportunities to see the scenery--yes, it IS beautiful! One of the relatives had a great-grandfather on the other side of the family who worked in the Lliechwedd cavern, so there certainly is interest from her perspective. I have looked into the Big Pit coal mine as well, but it really doesn't pertain to our family's history, so I was going to forego it and do the slate mining instead. Still undecided!
Note that Rick Steves has a separate forum for Wales - you have place a query about Wales in another country - England! However, they are both a part of Great Britain & it is a pity that RS does use that as the country category being as many people have queries about England, Scotland & Wales. (Scottish & Welsh Nationalists would prefer the present arrangement).