The Ponderosa Cafe on the Horse shoe Pass round Near Llangollen is always worth a visit on a sunday. If the weather is good it will be packed with bikes. It was the venue for the 2nd or 3rd Annual Rideout back in the days when I had a SV.
Just be aware of local Plod - they will pull you for anything in those there parts of the world.
http://www.ponderosacafe.co.uk/
Would be there myself on Sunday but Mrs GSX1400 just given birth to our second child on tuesday so I will be a bit busy this weekend.
Head south to Aberystwyth is also an option (about 2 hr straight run from Caernarfon) - Great roads , hardly any police once you get south of Dolgellau plus you get a trip to the seaside! The promenade Cafe in Aberystwyth usually got 50 - 70 bikes parked up outside most of the day if it's sunny.
Enjoy.