Upgrade from A3 to A2.
A3 is 29.7cm x 42cm. If you want to visualise this grab 2 A4s and pop them side by side (long edges together). This is A3. Not huge but great for smaller rooms.
A2 is 42cm x 59.7cm – double that the size of A3. This is much more classic 'poster' size. Much better for larger open spaces or where you want some more impact.