I LOVE LOVE LOVE linearrays, and I've built several the last few years. Here's the current version...
These are built with Sonic Craft 6-1/2" B/MR drivers, and they sound EXCELLENT if I say so myself*. These drivers are discontinued and soon will be unavailable, but probably the best thing about them, other than their basic very high sound quality, is that they're only $10 each in 24s. (I love 'em so much I just bought an extra carton of 24.) I used Parts Express's inexpensive Dayton mag.-planar tweeters, and while they sound good, the quality of the treble is NOT as high as that of the output of the B/MR drivers.
My systems are open-baffle, and they sound MUCH more-spacious than if they were sealed, but that's a personal preference. One thing I know--I'm never going back to a nonopen-baffle speaker system.
I think you need to do one of two things for tweeters--use one point-source** tweeter (and I'd use a ribbon tweeter by probably Aurum Cantus) or use a line of tweeters that are about as tall as your line of B/MR drivers. I think you'll hear lobing with 1"-dome tweeters; I know I and my friends did using 1" domes that were 2-1/2" center-to-center.
I'll soon be building finished versions with TWELVE B/MR drivers and (I hope) electrostatic tweeters by Roger Modjeski (Music Reference). These will be 2-ways, as are my current versions now since I've stolen those 12" woofers to use in my JB/JG-SuperSubs.
If Modjeski's tweeters aren't finished when I'm ready for them, probably I'll use some inexpensive single dome tweeter temporarily.
I'm actively filtering and EQing these with a dbx-brand DriveRackPA; I'm using (relatively) inexpensive Music Reference EM7 Single-Ended triode amps to drive them.
http://www.ramlabs-musicreference.com/EM7.html With a sensitivity of c. 100dB, they require little power to fill the room.
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* Others, too, say so, and if you'll e-mail me at jeffreybehr(at)cox(dot)net, I'll forward comments from a couple friends.
** Understand that the MR/treble balance from such a hybrid system will be correct at only one distance.