There is a thread over at Flyertalk regarding whether or not CL are open on weekends. You might want to consider checking it out: http://www.flyertalk.com/forum/marriott-ritz-carlton-rewards/1078647-master-thread-domestic-international-executive-lounges-open-closed-weekends.html
This is what is listed there for the Le Merigot:
* Santa Monica / LeMerigot, JW Marriott / NO LOUNGE; $16.95 credit towards breakfast for Golds/Plats M-F; 01/03/13 update
I highly recommend this property, and I've raved about it here: Santa Monica - Le Merigot, JW Marriott
I do not recall a concierge lounge (sorry), although the last time I was there, they were still renovating... But - both times I've stayed there - I've been comped breakfast at their wonderful restaurant (and I've eaten outside both times). I have really enjoyed that, and I've considered it one of the high points of my stay....