When shooting flowers I tend to switch from spot metering to evaluative and back again depending upon the light and subject. I think it's also worth deciding what you want to give weight to, either the flower as a whole or some detail and how the background will look. For example I'll sometimes go for a whole picture look with a nice background rather than go for absolute detail, depth or sharpness. For flower shots I do think that perspective and the final look are things to think about and that may well include a nice background even if that background just ends up as a diffuse colour.
Another thing to think about is I think final picture size and viewing. For example increasing the camera to subject distance may give you a different perspective and that may be what you want even if it means you have to crop the picture to get the final field of view look you want. That's shooting at long lens distance but using a shorter lens. I find that when doing this even a very heavy crop can still leave me with a picture that's large and good enough for my needs which are mostly for screen viewing and the occasional print to maybe A4. If doing this a macro lens may not be needed, if cropping gets you an acceptable end result.
I do have a macro lens but I'm not a big fan of extension tubes but I do very occasionally use close up filters.
