Where possible, use a solid ground plane with no interruption, as this will help deliver better wireless performance.
Ideally, you should have a minimum of a 4-layer PCB, especially if using a multi-band antenna. The stack up have a top and bottom layer of ground and all signal and power lines on the middle two layers.
If your design uses more than one ground layer, you should knit each ground plane together with evenly spaced vias to prevent ground paths.
Flood any free areas with ground as well to help with performance.