Cala D'Or is in the south east, a fair old schlep from Puerto Pollensa. Ninety minutes at best by car.

I really can't comment on the relative busy-ness of the two as I don't know Cala D'Or at that time of the year. With Easter the previous week, chances are that both will be relatively "open", though there are always establishments, wherever you choose, that do not open till 1 May. Cala D'Or has some lovely places nearby. Santanyi is a nice town and the Cala Mondrago is one of the best coves on the island. With respect to a respondent to your previous thread, Puerto Pollensa will generally be open at that time. As you like long walks there are some around Pollensa which are well publicised, such as that to Cala San Vicente.