My favorite starting lineups are:
Baynes, Horford, Tatum, Smart, Irving
Horford, Morris, Tatum, Smart, Irving (Pel's game starters)
I might lean toward the second, as with Hayward off the bench Morris becomes a nice starter.
And Morris is our biggest wing and thus it's not such a small group of starters to have him start at the 4. I like Tatum starting solidly at the 3.
End of games all bets are off...I'm sure we'll see all kinds of lineups...probably most of them smallish.
Hayward will be great of the bench and I think Brown can be too...let Marcus set the tone and do his thing...he's awesome and is perfect between Irving and Tatum.