2024 Grand Design Momentum 399TH vs 2025 Forest River Work and Play 21LT

Detailed Comparison

Two noteworthy RVs face off: the 2024 Grand Design Momentum 399TH and the 2025 Forest River Work and Play 21LT. From dimensions to amenities, here's the full breakdown.

In terms of footprint, the Grand Design Momentum 399TH stretches 28.0 ft while the Forest River Work and Play 21LT spans 41.0 ft. Weight-wise, the Grand Design Momentum 399TH is the lighter rig at 8,300 lbs versus 14,800 lbs.

Capacity-wise, expect to sleep 9 in the Grand Design Momentum 399TH versus 10 in the Forest River Work and Play 21LT. With 0 and 3 slide-outs respectively, the parked floor plans differ significantly.

Tank capacities are a key off-grid consideration. The Grand Design Momentum 399TH carries 68 gal of fresh water, 70 gal gray, and 50 gal black. The Forest River Work and Play 21LT offers 67 gal fresh, 67 gal gray, and 38 gal black. The Grand Design Momentum 399TH has the edge for extended dry camping.

Budget-wise, the Grand Design Momentum 399TH is listed at $61,000 compared to $62,000 for the Forest River Work and Play 21LT.

For family camping trips, the larger floor plan and additional berths make a real difference. For boondocking, the model with superior solar and battery setup will keep you comfortable off the grid longer. If you're going full-time, the larger tanks and more robust build quality matter enormously.

Both options have earned their place in the market. Your trip style and budget should be the final tiebreakers.