I have been using three Canon 600EX II-RT Speedlites for my real estate shooting for about 2 years now. For my style, I use one ambient exposure to show how the natural light falls into the room blended with up to three flash exposures to capture a rooms true colors without any deep shadows and color casts. On any given shoot, I have these three speedlites at the ready attached to pocket wizards and either mounted to tripods, mini-stands or a hand-held flash stick. Working in manual mode will allow you to adjust the power from 1/128 power to full power in 1/3 stop increments depending on your needs. The 600’s have the benefit of wireless slaving utilizing a 2.4GHz radio system which provides reliability and a wireless communication range up to 98.4 feet. You can use up to 15 speedlites in 5 groups if needed and don’t have to rely on “line-of-sight” communication between speedlites. I use these speedlites however, with Plus III Pocket wizards so that they will trigger in conjunction with larger studio strobes when I need to shoot large open areas. The 600EX II-RT is a compact yet powerful enough light solution for small to medium size rooms while larger rooms may take two speedlites. Using three 600’s along with studio strobes allows me to light main rooms at the same time I light hallways and rooms off the main in a single exposure which greatly reduces post processing time. If you use speedlites as part of your every day shooting I recommend equipping them with Panasonic Eneloop Pro rechargeable batteries. These batteries will last you for years and keep your costs down over the long term.