Public planters

Hi, I'm part of a community group trying to revitalise our local high street.  After a 'Street Day' on Friday 16th March 2012, one of the recurring themes of how we could help our high st was to make better use of our planters - a good floral display will brighten even the hardest heart!  We have two types of planter Type 1 (T1) = teak and metal construction, hexagonal, 57cm (external) Height x 52cm (internal) each side approx.  Type 2 (T2) = plastic construction (all internal dimensions) 93 w x 93 dx 21 h.  As a group we have no funding , so we need plants which will keep coming back each year with minimal maintenance whiole providing a good floral show. We would like to put some bulbs in this autumn in the T1 planters but need a spectacular display fot the Jubillee in June and trhe Olympic torch passing through in July.  Please can you help us?    Thank you vey much.