Hi Anna, actually for the most part those do not really scream out sub-d to me.

The one in the upper right is basically 3 stacked cylinders...

The one in the upper right has a very symmetrical revolved body. The petal parts at the top are getting more into sub-d territory though.

The heart one on the left seems to be symmetrical and mostly an extruded shape, that should be pretty straightforward in MoI I think.

The one on the right has a symmetrical main body and the petals are do not have very much fine level detail in them so they would be pretty easy to do with things like sweep. You might look at this previous thread to get some ideas:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1401.1


The green and red one is the least symmetrical in its main body, it does not follow a simple pattern to be revolved or extruded. But it still does not have a lot of little tiny details in it, so it still does not really cry out "sub-d".

Looking at it, you can kind of see that it kind of is made up of pieces stuck together - try to model it in that same way by making some independent pieces and then booleaning them together. Here is a quick time lapse of a couple of minutes of work, I started with a sweep at the bottom and then just placed 2 spheres which I squished, then boolean union and fillet:




If you can divide things out into a few predominate sub structures which can be combined together with fillets, then that tends to make it a good candidate for NURBS.

When there gets to be less and less definition of individual pieces within the shape, that's one indication that it is going more into sub-d oriented.

- Michael