I absolutely agree with your view of the relegation struggle in LaLiga. It certainly does look like Las Palmas are in severe peril following that Sevilla setback.   Their odds of staying up are increasing fewer by the day.  Alaves clearly have the superior position right now.   Hosting Valencia provides them a decent shot at points, however I'm not confident they'll get the win. A draw seems more realistic.   Valencia still has something to play for with the Conference League spot possibility, so they won't be taking it easy.

For Leganes, facing Villarreal away is just horrible timing.  I can't see them earning much from the match unless something extremely unexpected happens.
 You're right about end-of-season surprises though!   Every year we see some unexpected results in these final matches when relegation-threatened teams suddenly find another gear. Sometimes desperation generates amazing performances.The Alaves-Valencia encounter should be incredibly competitive with both clubs needing points for completely different reasons. I wouldn't wager on the match either - too uncertain with so much at risk.