Living in Denver is likely an advantage here.)

Probably a dangerous assumption. Oak expands and contracts substantially in
width, not length. You must allow for the expansion of the ends of the
table/breadboard interface or you'll end up with cracks or other problems.
I really don't think Denver's climate will help.

I see some techniques for using splines to attach the breadboards.

My question is - wouldn't biscuits accomplish the same thing?
Biscuits allow for lateral movement - assuming I just put a small dab of
glue on the biscuit center, right?

I have done this. However, I did it with an 8/4 Oak coffee table top which
allow more design latitude than 4/4. I'll try to describe this. If you
need a sketch I'll work something up and email.

Imagine looking at the end of a 8/4 x 22" slab:

1) I placed 12 biscuits in three groups of four. Each group of four
consisted of two each 1/2" inside of the upper and lower surfaces. A
visualized rectangle of four biscuit centers was roughtly 1" x 4" - again
1/2" inside of outside surfaces.

2) One group was centered in the middle of the slab. The other two were
placed, with outer biscuit slot edges, about 1" from the end of the slab
(after slots are elongated, below).

3) The slots for the center set were cut as you normally would - tight fit.
Also I placed two 1/4" lag screws at approximate center of the biscuits.
The breadboard end was drilled to match and partially mortised to accept a
decorative plug.

4) The EDGE groups of biscuits:

4A) In the TABLE SLAB, the biscuit slots were cut normally - tight. Also
located one 1/4" lag screw in the center of the group.

4B) In the BREADBOARD, the biscuit slots were elongated to allow 3/8"
slippage, in each direction, at the bottom of the slot (3/4" bottom flat
slot). Also, the matching lag screw hole was elongated to 1/4" x 1". Again
a mortise for decorative plug was cut at each location.

5) Important - ONLY THE CENTER LOCATION IS GLUED. On this project I glued
the center biscuits in place and surface glued approximately the center 6" -
8" of the table/breadboard interface. These two lag screws were fitted with
washer and lockwasher and tightened to moderately hand tight.

6) The outer groups were LIGHTLY GLUED INSIDE OF THE TIGHT BISCUIT LOCATION
only (table slab). The oversized slots were left dry. The lag screw at
each location was similarly washered, moderately tightened, and backed off
about 1/4 turn.

Here again, the 8/4 stock allowed some latitude by allowing me to place the
bolts inside of the biscuit patterns. Also, on the unglued end, the bolts
are really providing a large part of the strength. Since I was already
using contrasting hardwoods, I plugged the bolt mortises with curly grained
walnut to match similar wood used elsewere. With 4/4 stock you'l have to
arrange differently. Don't depend on lightly glued biscuits alone to hold
things together. You're liable to end up with mashed potatoes in you lap.

I'll post a pic of the table at ABPW to give you an Idea of what I'm talking
about. If the gibberish above isn't clear enough let me know and I send you
a sketch (quickly, I'll be gone a for a couple of days.)

I need to whack this thing out quickly and am tyring to strike the balance
between moving fast and having something worth keeping longer than a few
years.

Always a nobel goal.

thank you!