Interviews with vendors:how to walk away?

[galephys]

I was doing a lot of interviews lately, and I realized I feel guilty walking away.
I did cake tasting, and the lady already filled the contract form and gave me to signs, without even asking if we want to go with them or not! Salesperson in the dress shop urged me to schedule another appointment or order the dress now, but I am just going around, trying styles and will order my dress online.
So, how do you tell them now? I sort of feel guilty after they spend so much time with me, give me free cake, and I don't want to go with them.
Also, how does menu tasting works? We need to try beer, wine and entries. We picked 2 entries for now, but wine and beer - no idea. How many drinks do you try? Do you finish the meal they give you? Hell, just tell me how it worked for you, please.
How does it work with florists: you come, tell them how big is your party and what do you want for decoration, and then what?

I'm going to look for the dress tomorrow, then a meeting with a bakery and a florist next week and tasting later that week too. Please, help.