I wish I could say this was my idea, but it wasn't. A few years ago I did the Llantwit Major to Monknash walk and saw a bunch of drunk people getting the 145 bus from Monknash and then jumping off a couple of miles down the road at the next pub. When I got home I took a look at the route and discovered it goes past a few nice pubs and was rather a good idea.
Like many of these walks this is not doable on a Sunday.
Take the train to Llantwhit Major. These are hourly from Cardiff and will get you in at 31 minuets past. You then have wait for 24 minuets. If you decided to go for a drink while you wait I recommend The Old Swan Inn and The Old White Hart (45.5%).
The 145 bus (time table) leaves from the bus stop right outside the train station. Buy a day ticket which is around £3.50. From here on you can jump on and off the bus as much as you like and take in all the nice pubs on the 145 route. I've created a nice gmap of the crawl. These are in order:
1. The Hourseshoe Inn, Marcoss 86%
2. The Plough and Harrow, Monknash 82.5%
3. Lamb & Flag Inn, Wick 42%
4. The Star Inn, Wick, 46%
5. The Farmer's Arms, St Brides Major unscored
6. The 3 Golden Cups, Southerndown unscored
7. The Pelican In Her Pieti, Ogmore 58%
The scores are all in the 2011 pub score system that will be the subject of another post, but as you can probably guess the higher the score the better the pub.
Keeping jumping on and off the bus as you feel like it visiting a selection of the pubs. Remember you can travel in either direction. You can end the crawl in either Llantwhit Major or Bridgend and get the train back to Cardiff.