Hi Sharon
I spent some time in Monteverde in June-July a few years ago. There's a lot of small guesthouses, esp. in Santa Elena, and I think most of them are fine places to stay - I never met anyone who was unhappy with the places they stayed at. If you want to have a choice of places to eat/drink in the evening Santa Elena is probably your best bet.
For birding it's definitely worth doing some hill walking to explore the forest at different elevations as you get different species at different elevations on the slope. I'd also recommend the "sky-walk" in Santa Elena - they have suspension bridges going across gorges so you're at canopy level of the trees growing in the gorge. This gives you a completely different perspective than you get from ground level and the chance to see species that you'd almost never see otherwise as the vegetation is far too dense to be able to see canopy species from the ground. You also get a great view of some of the epiphytic plants that completely cover the branches of the trees. Some of these plants are spectacular. I was also lucky enough to see (and hear) howler monkeys from the sky walk.
Keep an ear out for three-wattled bellbirds - as their name suggests they have an unmistakeable bell-like call. You're unlikely to see one though, as they tend to stay high in the canopy. Your best chance would be looking down a steep slope where you can see through a chink in the vegetation to the canopy level of trees growing further down slope. Of course you have to be lucky enough that one happens to be sitting in the small bit of canopy you can see - it's unlikely but worth checking out if you happen to be able to hear one calling from such a place. Another species to look out for is long-tailed manakin (mid-slope elevations). You may be a bit early in the year to see males displaying though (but I'd really recommend going another time in April-July to see this - one of the most amazing things I've ever been lucky enough to see. They are really cool little birds. They display from low horizontal(ish) branches or vines in the understorey, and routinely use the same display perches so a local guide may be able to point you in the right direction). Another species that's really beautiful is the spangle-cheeked tanager - mostly found in the cloud forest, and of course all the hummingbirds are great. If you want to get good close-up views of hummingbirds they have a load of feeders near the visitor centre at the Monteverde reserve where you can get really good views of several species. Other species you should get good views of include blue-crowned motmot, emerald toucanet, keel billed toucan and many more.
One "must have" is a copy of Stiles and Skutch, and I would make sure to learn about some of the tricky species before you go (wrens, elaenias, flycatchers, euphonias and treerunners/woodcreepers/foliage gleaners are all difficult if you don't know what to look for).
Finally, try to go up to the top of the continental divide on a clear day if you can. You'll need to have flexible plans for this as it's ofen cloudy, surprisingly, in cloud forest ;-). Here you'll see the "elfin" forest (all the trees are stunted because it's so exposed) and get great views - apparently you can see the Caribbean and the Pacific on a clear day, but it was very cloudy on the days when I went up so I missed the view!
Hope that helps. I'm afraid I'm not familiar with the other areas you're planning to visit so can't make any suggestions.
Have a great trip!
Lucy