We really enjoyed our first visit to Vale's and plan on making a return trip when we have more time to spare. I would estimate you would need ~1.5 hours to carefully peruse all of the greenhouses and the gift shop. The staff were knowledgable about their inventory and were able to direct me to the exact green house and/or cold frame where my enquiries were waiting.
They have an excellent selection of perenials and annuals, including items I wasn't able to find in the city. I was specifically looking for Nicotiana Alata or Sylvestrii, and they had the latter. I was also able to purchase a couple of other talls for the border, foxglove (Digitalis) and Bells of Ireland.The drive out (22X) was very nice too, thru the rolling foothills!