Do I need two armrest trays for a sectional?

Yes, one for each end. Both ends tend to be the most-used seats, and both need a drink surface. Two trays are still cheaper than one bad sectional accessory.

What size throw works for a sectional?

At least 60 by 80 inches to cover three people. Standard throws are 50 by 60, which only cover one person. The bigger throw is the difference between a useful throw and a decorative one.

Do I need a special lamp for a sectional?

A regular floor lamp works. The important thing is positioning: place it near the most-used seats, not in the corner. Sectional lighting is about where the lamp is, not what kind.

The few sectional sofa accessories worth buying

What sectionals do not need

Most sectional accessories on Amazon are wrong for the actual problem. The big offenders:

Sectional ‘cup holder organizers’ that try to wedge into the gap between cushions. They scratch the cushion sides and slide.
Lap trays sold as ‘sectional accessories.’ The lap is a lap. Any tray works.
Sectional covers. They slide off and look temporary, like a couch wearing a hospital gown.
‘Sectional organizers’ that hang off the back. They flop forward when sat on and look like a back-of-seat airplane pocket.

What sectionals actually benefit from

An armrest tray on each end of the sectional. Drinks for the people in the good seats.
A real sectional-sized throw. Most throws are too small for a sectional. Get one in the 60 by 80 range, washed weekly.
A wedge cushion or thin lumbar pillow for the back corner of the L-shape. The corner of an L-sectional has bad back support without a wedge.
A floor basket near the chaise end. The chaise has nowhere to put books, magazines, or the daily pile. A basket solves it.
A corner lamp positioned near the ‘good’ seats. Most sectionals are too long for a single overhead light to be enough.

Why these five and not others

Each of these fixes a real friction that sectionals have specifically. The L-corner has no back support. The chaise has no surface. The good seats need light. The drinks need a home. The throw needs to be big enough to cover three people if needed.

Other accessories address problems that sectionals do not actually have, or address them in worse ways than the five above.

The wedge cushion specifically

Most sectionals have a corner seat at the elbow of the L-shape. This is the worst seat in the section for back support. The cushion is square (because the corner is square) and the back has nothing to lean against on one side.

A wedge cushion or a thin lumbar pillow in the corner fixes this. Not glamorous. Surprisingly important for whoever ends up in the corner seat.

About the trays specifically

Sectionals usually have wider armrests than standard couches, in the 6 to 9 inch range. A standard couch tray fits, but a slightly wider tray is more stable.

The Sofa Sidekick is 11 inches wide and fits sectional armrests in the 6-9 inch range. The cup well sits in the center. The flat tray has room for a remote and a phone. The tray drapes about 4 inches down each side of the armrest, which anchors it on a smooth leather or microfiber sectional.

The honest budget

Total cost for the five-accessory sectional kit: about $200. Two armrest trays at $30, a sectional throw at $50, a wedge cushion at $25, a floor basket at $35, a corner lamp at $30.

Skipping the wrong accessories saves about $300 in things that get returned or put in storage within a month.

Sectionals are big-ticket purchases. The right accessories make them functional. The wrong ones make them cluttered. Spend on the five above. Skip the rest.