30 Days stay

The fine and repercussions are best avoided. I always go at 28 days, because if there is a travel problem, you will be caught out. It is easy to get to Bahrain by VIP bus, SR196 return, 4 1/2 - 4 3/4 hours to Khobar. There is a connecting bus to Manama (SABTCO) SR100 return. Leave 09.00 Saturday morning, you can be back in Riyadh by about 01.00 Sunday morning. Pay a little more and get a taxi to the immigration post on the causeway. You need only to go in, then come back without proceeding to Manama. Yes it takes a day, but you can relax on the bus, and admire the interesting scenery.

Give yourself a buffer as sometimes authorities at causeway will not let you let you exit from causeway. More relevant in case of Indians and Pakistan. In case of a cock up save yourself a hefty fine and hassle.

Actually i go to India everytime for exit/entry, and stay there for a week. My problem is that i get paid for each day, so if i exit on 28th day i loose 2 days pay...!
But its better to be on the safer side i think...!

Thanks