# Perl, score: 2655 <s>2630</s>

    #!perl -l
    %p = qw{A 1 B 3 C 3 D 2 E 1 F 4 G 2 H 4 I 1 J 8 K 5 L 1 M 3 N 1 O 1 P 3 Q 10 R 1 S 1 T 1 U 1 V 4 W 4 X 8 Y 4 Z 10 x 0};
    /[A-Z]+/,push @R,$& for <>;
    @R = sort{length($b)<=>length($a)}@R;
    for(@R) {push@W,$_;push@W,"$`x$'" while /./g;push@O,($_)x(1+length)}
    $l = "AAAAAAAAABBCCDDDDEEEEEEEEEEEEFFGGGHHIIIIIIIIIJKLLLLMMNNNNNNOOOOOOOOPPQRRRRRRSSSSTTTTTTUUUUVVWWXYYZxx";
    @S = map {$r='';for$x(A..Z,'x'){$r.="${x}{".(1*s/$x//g).",}"};"^$r\$"} map{"$_"}@W;
    sub score{$r=0;$r+=$p{$_}for split'',$rr=pop;$r*length$rr}
    @X = map{score$_}@W;
    $f = 'x';
    for(;;) {
    $best = -1; $besti = 0;
    for ($i=0;$i<@S;$i++) {
        next if $X[$i] < $best;
        if ($O[$i]!~/^[$f]/ && $l=~$S[$i]) {
    	$best = $X[$i];
    	$besti = $i;
        }
    }
    if($best < 0){
        $ls = score$l;
        print "left: $l (-$ls)";
        $tot -= $ls;
        print "total: $tot";
        exit;
    }
    $l=~s/$_// for $W[$besti]=~/./g;
    $O[$besti]=~/./; $f .= $&;
    print "$W[$besti]/$O[$besti] ($X[$besti])";
    $tot += $X[$besti];
    }

Use:

    $ perl ./scrab.pl <~/sowpods.txt
    OXYPHENBUTAZONE/OXYPHENBUTAZONE (615)
    MICROEARTHQUAKE/MICROEARTHQUAKE (525)
    NONOBJECTIVISMS/NONOBJECTIVISMS (465)
    DAFFADOWNDILLY/DAFFADOWNDILLY (406)
    PREINTERVIEWIxG/PREINTERVIEWING (345)
    LITURGIOLOGxSTS/LITURGIOLOGISTS (240)
    URDEE/URDEE (30)
    EE/EE (4)
    AA/AA (4)
    left: AA (-4)
    total: 2630

Use of blanks actually does not give that much while significantly slows down the execution:

    $ perl ./scrab.pl <~/sowpods.txt 
    OXYPHENBUTAZONE/OXYPHENBUTAZONE (615)
    MICROEARTHQUAKE/MICROEARTHQUAKE (525)
    NONOBJECTIVISMS/NONOBJECTIVISMS (465)
    DAFFADOWNDILLY/DAFFADOWNDILLY (406)
    PREINTERVIEWED/PREINTERVIEWED (322)
    LITURGIOLOGISTS/LITURGIOLOGISTS (255)
    RUGAE/RUGAE (30)
    EE/EE (4)
    AA/AA (4)
    left: Axx (-3)
    total: 2623

After adding some heuristics:

    $ time perl ./scrab.pl <~/sowpods.txt 
    OXYPHENBUTAZONE/OXYPHENBUTAZONE (615)
    MICROEARTHQUAKE/MICROEARTHQUAKE (525)
    NONOBJECTIVISMS/NONOBJECTIVISMS (465)
    PREFIGURATIVELY/PREFIGURATIVELY (405)
    DOWNREGULATIONS/DOWNREGULATIONS (300)
    FORGEAxILITIES/FORGEABILITIES (238)
    ADWAxDED/ADWARDED (104)
    EA/EA (4)
    left: L (-1)
    total: 2655
    
    real	3m58.517s
    user	3m57.832s
    sys	0m0.512s