I figured that the techs would know best
that is where you are wrong, you would know best they are your teeth and you should have what ever color you would like
if you want purple teeth that is your decision
true, however to directly answer the posed question one might say if B1 is too dark, and A1 is too yellow, try the ivoclar 020-030 shade. brighter without being un-naturally white.
it would not be my preference to send you into such white colors, but that is a shade that is whiter than B1.
b1 is already pronouncedly whiter than most of the restorations we see on a day to day basis. in a dark room (i.e at a club) you will see B1 as a nice bright white. in the superbrightly lit dentists office it will appear yellow. this is natural.
020-030 shades even moreso.
this is of course entirely subjective as was pointed out above. only you can determine how you want to look and even if you wanted purple teeth - thats what you want and we as technicians must comply with that.
re: shape, look at a chicklet. now look at your teeth. if the teeth match the chicklet, you have square, shape. if this does not please you esthetically, ask for rounded distals, or characterization on your buccal area. verbally its difficult to communicate what a smile should look like, however every good dentist has a "smile catalog" at the office for you to look through and determine if the shape of the teeth look nice to your features. all must be discussed with the attending dentist.
technicians tend to get... rather technical.