I have BCBS standard and agree with the other PP that it doesn't cover much at all regarding dental cleanings. I don't know why someone upthread said it does- it doesn't.
We've never had separate dental coverage but looking into it now as one child will likely need braces soon. No advice yet as I've just started looking at dental plans. But BCBS standard has covered all of my pregnancy costs and specialist visits for other health issues.

I've had BCBS Basic for 10 years. My pregnancy and delivery cost $100 or $150 I forget exactly (plus the TV fee the hospital charged - ha!). All healthy child visits are free too. I've never had trouble finding an in-network doctor even when we've had to go to urgent care centers while traveling. The only doctors that I've found that don't take BCBS don't take any insurance. We had dental insurance for one year when my DH needed his wisdom teeth out. They only paid 50% or something and the premiums were pretty expensive so I'm not sure in the end it was worth it. Try pricing it out. Dental insurance is generally not worth it if you only need occasional minor dental work.