For page blocks you may use widgets. There’re also clips, partial view render , content decorator, so you’ll easily form your pages.
As for UI, you may implement any css framework (bootsrtap, foudation) or one of yii-extensions based on them. For example, http://www.yiiframework.com/extension/bootstrap is quite popular.
Also, there’re yii-adapted jquery-ui tools, just go to http://www.yiiframework.com/doc/api and type CJui into search input to check them all.
http://twitter.githu…trap/index.html is the source of the bootstrap toolkit developped by Twitter.
Yii-booster is an adaptation of all the bootstrap tools (css stylings and javascripts functionnalities) plus some extra additions in the Yii’s way, mostly as widgets (and CWidget subclasses)
bootstrap is mostly a css toolkit => it decorates, quiet well I have to admit, your forms, tables and so on. So If you use Yiibooster (or bootstrap extension from Chris83) and if you want to show your data in a grid (saying in the admin view grid as generated by gii), instead of using