These hymns from the Common of the BVM could be used on the Solemnity of the Immaculate Conception

For the most part the hymns assigned to this Solemnity in the LH are late and somewhat less pleasing. The 1963 Monastic Breviary for this day uses Praeclara custos Virginum (in my opinion the best of the hymns provided for the feast) for Matins but O gloriosa Domina for Lauds and Ave, maris stella for Vespers. 

Vespers: Common of the Blessed Virgin Mary: 9^th Century?

Ave, maris stella,

Dei mater alma,

atque semper virgo,

felix cæli porta.

Sumens illud «Ave»

Gabriélis ore,

funda nos in pace,

mutans Evæ nomen.

Solve vincla reis,

profer lumen cæcis,

mala nostra pelle,

bona cuncta posce.

Monstra te esse matrem,

sumat per te precem

qui pro nobis natus

tulit esse tuus.

Virgo singuláris,

inter omnes mitis,

nos culpis solútos

mites fac et castos.

Vitam præsta puram,

iter para tutum,

ut vidéntes Iesum

semper collætémur.

Sit laus Deo Patri,

summo Christo decus,

Spirítui Sancto

honor, tribus unus. Amen.

Hail, Star of the Sea, loving Mother of God and ever a virgin, fair gate of heaven. You who received the “Ave’ from the mouth of Gabriel, establish us in peace, reversing the name of “Eva”. Break the chains of sin, give light to the blind, drive away our evil, ask for us all that is good. Show yourself a mother, may he who was born for us and humbled himself to be your Son, receive our prayer through you.  Virgin alone, meek beyond all others, cause our sins to be absolved, make us meek and chaste. Make our life unsullied, our journey safe, that we may see Jesus and with you praise him forever. Amen.

Lauds

O gloriósa dómina

excélsa super sídera,

qui te creávit próvide,

lactas sacráto úbere.

Quod Eva tristis ábstulit,

tu reddis almo gérmine;

intrent ut astra flébiles,

sternis benígna sémitam.

Tu regis alti iánua

et porta lucis fúlgida;

vitam datam per Vírginem,

gentes redémptæ, pláudite.

O glorious Lady exalted above the stars; He, who providentially created you, you nurse with your sacred breast. What sad Eve took away you return by your nourishing seed; that weak men might go to the stars you kindly provide a path. You are the door of the high King, the brightly shining gate to light; applaud, nations redeemed, that life is given through a virgin.