According to the latest version of NAS it is also recommended that higher performance aircraft (usually IFR), will use a higher circuit altitiude, I know I do! I will also where possible/practical use a straight in approach to minimise conflicts with circuit traffic...
PS: If doing an instrument approach with VFR's in circuit, I will always try and let them know my intentions in VFR friendly terms, (no NDB outbound/inbound etc)...