OP: You won't want to book different cabins by segment. That will lead to a broken fare and additive pricing. You may book different cabins in each direction, as in Delta One going and Comfort+ returning.

Good: CLE-JFK-PRG as a single fare component in domestic First/Delta One

Bad: CLE-JFK in Comfort+, JFK-PRG in business, pricing as a domestic redemption + TATL redemption

You really should be talking to a Delta res agent to initiate a booking.