Hi Pavel,
When do you plan to go and what sort of conditions are you looking for? I have not been to Las Barriles but have been to La Ventana. Many members here go to LV religiously. If you are looking at strictly Baja then LV would be the place to go for wind sports I suspect. My wife and I went March, 2018. LV got hit with a strong El Norte while we were there which made for REALLY challenging conditions. I went for fun, civilized conditions and the El Norte made the wind sport side of the trip disappointing (the main point of going). Still was an interesting trip overall though. If you like those type of conditions, go but be warned. If you prefer flat water sailing be warned that depending on the time of year you may go and get punished in LV.
Unless you are committed to Baja or Mexico in general, I suggest an alternative; TOBAGO. Having been to both in the winter for wind sports I'd take Tobago again over LV in a heart beat. Nice flat water Caribbean logoon sailing. If you time it right you can coordinate with carnival in Trinidad (Port of Spain) which is what we did. Further, coaches like Jem Hall, Guy Cribb, and Peter Hart run regular clinics out of Tobago if you are in to that sort of thing. Jem Hall's beginner to Winner instructional Windsurfing video was filmed there.
If you go to LV, contact Wyatt Miller and Tyson Poor with Pro Windsurf La Ventana: You can book everything through them from gear to accommodation. All you need is your flights. Most will agree, if you go to LV for windsurfing, Wyatt and Tyson with Pro windsurf LV are where you must be. They are wind and water wizards.
https://www.prowindsurflaventana.com/If you do Tobago then Brent Kenny with Radical Sports is the man and place to contact. Same, I believe you can book everything with them. Just need flights. They have everything you need from lessons to gear. The vibe is awesome.
https://www.radicalsportstobago.com/We booked our Tobago trip through Vela Watersports for convenience. If (when) we go next time we'd probably just book directly with the providers and skip Vela as the middle person (save a few bucks). Contact Radical Sports for the windsurfing side and Shepard's Inn for the accommodation. Then book your own flights to Tobago (likely through Port of Spain).
https://velawatersports.com/https://www.shepherdsinntobago.com/Both are top-notch full-service wind sports providers and destinations. I feel your family may have a more interesting time in Trinidad/Tobago though if they are not in to wind sports. LV is fun but it's a bit more "rustic" and your family may get little board unless you are there just a few days. To me, LV feels like a hold-me over destination. Tobago feels like you really went on vacation/adventure. My 2 cents.
Mark